Replace Hand Sanding with Power Sanding

Bodyshop Business (www.bodyshopbusiness.com) has a new, updated website that includes links to articles that were published years ago in their print magazine. Here's a portion of one of their sanding related articles from March 2010 titled "Why You Should Replace Hand Sanding with Power Sanding":

Removing Material

This is the portion of the work that’s seldom done by hand by anyone. All you vo-tech grads probably still have the long board (a.k.a. the idiot stick) that you started school with and maybe even drag across a troublesome panel once or twice a year, but in large part everyone recognizes that removing old finishes or shaping body filler is a job for power tools. This rough work can be accomplished quickly by using a:

• Grinder. While the 24 or 36 grit 7-inch grinding disc will rip material off the surface fast, it also generates lots of heat. Any tool spinning at 3,000 to 5,000 rpm gets the sandpaper and the surface really hot. When you get the old paint or new body filler hot, it melts and clogs the expensive grinding disc. Let’s not forget also that it takes a manly man to shape filler with any kind of finesse when the tool is heavy and whirling at 5,000 rpm.

The other part of the equation is that once the material is ripped off with the grinder, the tech now has to fill and smooth those 24 grit scratches, adding more labor time to the repair. A better choice to strip paint and shave filler with 36, 40, 50, 60 or 80 grit paper might be a hog sander.

• 8-inch hog sander. This tool operates at a much lower rpm (900 to 1,000) and therefore runs much cooler. Because it spins slower, you can sand off the material with a paper disc rather than cloth. Materials are much cheaper. Whether this style of tool runs in a rotary (straight circle) or a rosette (offset circle) pattern, it removes the old finish or the body filler quickly and with lots of control.

To get the maximum benefit, make sure to hold the sander flat against the surface rather than up on the edge like a grinding disc. There are still some techs who think that to keep a long panel straight, they need a tool with a longer pad than the 8-inch round ones found on this style of sander. They prefer to use a file board.

• File board. With a 2-3/4-inch by 16-1/2-inch pad, this powered “idiot stick” is the staple of the industry. If you’re old enough, you remember when this tool was equipped with a 14-inch metal file rather than a sanding pad, and metal men used them to power-file down high spots in the steel and shave body solder (lead). Hence the name “file board.” Today, virtually all file boards are equipped with sanding pads. These tools can run in a straight line (back and forth) and be powered by a single piston with two ringed ends or by two pistons, one to push the pad forward and the other to push it back. Or they can run with an orbital wiggle (jitterbug) pattern.

Both styles have their advocates and strengths. In either case, it’s a great way to keep a long panel straight and chop off unwanted material quickly. Keeping piston-driven air files well lubricated will minimize the stalling of the pad. When the air pressure is equal on both ends of the stroke, the tool won’t start up when the trigger is depressed the next time. Many techs slam the end of the sanding pad to get the tool started back up, but keeping the cylinders well oiled is the key. And just a light push on one end or the other will start the tool back up smoothly.

Shaping the Surface

Shaping sanders are tools designed to prepare surfaces for paint. Power sanders do this rapidly, increasing the adhesion of the new coatings and featheredging the chips in the old finish. A smaller version of a file board sander with a straight line action could also work well to block the surface flat.

Prior to 1957, this type of sanding was often done by an orbital sander with a 3-inch by 8-inch or 3-2/3-inch by 9-inch pad called a jitterbug due to its wobbling action. Orbital sanders with various size pads are still useful today. Several sander manufacturers offer square or rectangular pads on a drive motor with a 3/16-inch orbit. In fact, most tools in this category (based on my arbitrary definitions) have a 3/16-inch or larger (3/8-inch) stroke – fast and aggressive enough to quickly shape and prepare the surface.

Just a reminder about how important thorough sanding is to ensure adhesion of the new coatings. It’s possible to double the contact of the surface area by sanding it well. How can that be? Imagine a distance on a flat surface from point A to point B. Now sand that same area and the distance from A to B (the contact area for the new coating), including the surface on both sides of the scratch (trench). Down one side of the scratch, up the other, down the next, up the other side – you get the idea. It will provide twice the surface to stick the new finish to.

A rotary or orbital tool runs the pad in a circle. A random orbit sander runs the pad in two circles, one inside the other. In 1957, the National Detroit Company patented the first random orbit sander widely used in refinish. In an effort to describe the circle-within-a-circle pattern, they called it “Dual Action.” It has become so pervasive in the market that its brand name has become a generic term. So when you say “D/A,” you likely mean a random orbit sander, now made by dozens of quality companies – kind of like when you say Kleenex and mean facial tissue, originally made by the Kimberly-Clark Company, or when you say Bondo® (a trademark of 3M Company) and mean polyester body filler, originally made and successfully marketed by the Bondo Corporation (now 3M Company). Or, if you’re in the South and say Coke, you really mean a carbonated soda made by any one of dozens of brands!

In this middle category of power sanders, most random orbit tools use either a 3/8-inch (very aggressive) or 3/16-inch (less aggressive but still fast) offset. The size of the offset determines how far the pad travels in each rotation. Bigger offsets cover more area but cause the tool to vibrate more.
In addition, some of these tools have a built-in wobble in the pad that interrupts contact with the work surface, and with the pad always changing planes, the sandpaper doesn’t load up as quickly and the pad runs cooler. What sort of wobble? Take a dinner plate, set it on its edge and spin it like a top. As the plate slows down, it will wobble through the last few rotations just before it stops and lays flat again. The pad works the same way, lifting its edges at the outside, allowing the sanding residue to be cast out from under the pad.

Sandpaper grits that would be used in this shaping tool segment run from 80 to about 400. By the way, there’s a two-grit jump from hand sanding to machine sanding. For example, if the tech hand sands with 400 grit, he or she can get the same scratch by using 320 grit on a random orbit power sander. The power tool moves much faster. As another example, if the tech runs 180 grit on the D/A, he or she will need to move up two grits to 240 grit to get the same scratch by hand. In many shops, it’s common to see the painter run a random orbit sander with 320 grit and then hand sand the same area with 400. Hello, it’s the same scratch! So stop hand sanding, or at least move to 500 or 600 grit to see a finer result.

Race to the Finish

This is the point at which many techs pick up the rubber block or foam sanding pad, believing that the sanding must be done by hand to get quality results. In addition to a change in attitude, they need a very smooth-running sander! Final block sanding can be accomplished with super smooth versions of almost every tool we’ve described so far.

A straight line sander with a small stroke and velvety action is how craftsmen achieve the high-gloss finish on fine wooden furniture. Orbital or random orbital tools at this level will have a smaller offset, typically 3/32 inches, half or less than the sanders previously listed. These tools will remain in contact with the work surface (no pad wobble) and run in a nice, silky stroke. The three main offsets for random orbit sanders get smaller by half each time. The largest, most aggressive offset is 3/8 inches (6/16), with the next being half that or 3/16 inches (6/32). At the final finish level, the typical offset is a short and smooth 3/32 inches.

In my experience, small-stroke, smooth-running sanders are the type missing from many techs’ toolboxes. The reason, I believe, is techs’ fear that these sanders won’t run smoothly enough and be controllable enough to ensure the work will turn out perfect. Also, these tools are expensive, and power-sanding final detail work requires a change in procedure that many techs are uncomfortable with. In the end, far too many folks pick up a rubber block and scrub away at the surface at 67 cents per minute ($40/hour) labor time. If you buy the idea that more work could be done at the same or better quality, then you’re in the market for a super smooth power sander.

Pads: 5-Inch or 6-Inch?

Two common choices of pads are 5- and 6-inch diameter models. There are still some painters who use 5-inch pads, arguing that they can get closer to the edges and moldings with smaller ones. If you’re one of those folks, please do this little test: Take a 5-inch sanding disc and a 6-inch disc, and lay the 5-inch disc as close to the corner of a piece of notebook paper as you can while still keeping the whole sanding disc on the paper. You can’t get any closer to any car molding than this. Draw along the edge of the disc. You’ll have a curved line about a half-inch back from the corner. “See how close I can get?” say the 5-inch disc advocates.

Now take the 6-inch disc and slide it as close to the edge of the notebook paper as possible and draw a line on its curved edge. Guess what? The line from the 6-inch disc is within 1/8 inches of the 5-inch line. My point is that the 6-inch disc will get just as close to edges and moldings as the 5-inch one, but it has 44 percent more surface area. The tech would sand 44 percent longer between disc changes and the cost is only about 35 percent more per disc – a bargain and a great production aid, too! The final finish power sanding I’m describing will require sandpaper grits from about 400 up to 2,000. Remember that two grit jump: 1,200 on a D/A is about the same scratch as 2,000 by hand.

All Wet

Much of the work at this level is the sanding required on the clearcoat prior to a buff and polish. As much as 90 percent of this work is done with dry sandpaper, but I contend there is still a place for power wet sanding. Extra fine grits of dry sandpaper work so well because the abrasive manufacturers have done wonders with the lubricants they build into the latest versions of today’s papers.

The very first lubricant added to dry sandpaper was zinc stearate. These sandpapers were white instead of brown and were advertised as no-load or free cutting. The residue from sanding is correctly called “swarf.” It’s composed of both the sandpaper disintegrating and the dust from whatever you’re removing. Lubricants in sandpaper help to slide the swarf out of the way. Current dry-sand fine-finish papers use an even more sophisticated lubricant to prevent the paper from loading.

Wet sanding has always been useful for making sandpaper last longer as the water washes the swarf completely out of the way. The water also acts as a lubricant, cools the surface, extends paper life by three to five times and, when final sanding clears, allows for a bigger margin of error. The error we’re talking about is the clear resin that re-forms into a ball from the sander’s heat and gets caught under the pad.

I contend that painters who still hand-sand do so because they tried power sanding and dragged a ball of clear across the finish and left a 220 grit-sized scratch they couldn’t polish out. Fine finish wet sanders either pull water up to the surface by suction (caused by the rotation of the pad) or force-feed the water by connecting the sander to a faucet. Because the water will flush the surface completely, the chance of dragging a lump of melted clear across the finish is minimized.

The downside of wet sanding is that it’s messy, it can rust the tool’s components and it’s potentially dangerous when the floor gets slippery. One solution is to wet-sand using a spray bottle of water to flush the swarf away. If you prefer to dry sand, make sure to use plenty of interface pads, which act like a cushion and soften any contact between pad and work surface. Vacuum attachments will also serve to collect any hunks of swarf before they can damage the clearcoats – and keep the shop much cleaner too.

Some great information, huh? If you'd like to read the complete article, here's the link: "Why You Should Replace Hand Sanding with Power Sanding"

Using sanding discs for refinishing your wood deck...

10 Steps for Refinishing Your Wood Deck:

1. Inspect the deck for any repairs that may be needed. Check for loose boards and nails or screws that may have worked their way out of the wood. Make any necessary repairs to insure that the boards are even and the nails or screws are set just below the surface of the decking.
2. Sweep the deck surface to clean any twigs, leaves or pebbles from the surface.
3. If you need to get rid of any mildew buildup, scrub the area with a combination of water and household bleach or use a commercial deck cleaning product.
4. If your deck is discolored or older and neglected you may need to use a power washer. After washing, let the deck dry completely.
5. Prepare to sand the deck surface. Since the process of sanding involves the removal of material it creates airborne dust. Please wear safety glasses, work gloves and an approved dust mask/respirator.
6. The easiest way to sand off the existing finish is to rent a random-orbit floor sander that uses sanding discs. These are gentler than a drum or belt sander on the wood.
7. You can purchase sanding discs through your rental store or an online supplier of sanding discs for floor sanders. Start with an 80 grit to get down to the fresh wood and roughen the surface. Proceed carefully, taking off only as much wood as needed.
8. Go back over the decking with a 120 grit sanding discs as your final sand prior to the application of stain or sealer. Sanding the wood opens it up for better absorption of the finish.
9. When done sanding, sweep or vacuum all of the dust away. The more thorough your cleaning job is, the better the finish will absorb.
10. Coat the deck right away with your finish of choice, following all manufacturers’ instructions for application and safety. Research by the US Forest Products Laboratory shows that even a few days of exposure to sunlight can affect the wood's ability to accept stain properly.

Sandpaper for Autobody Repair

The December 2011 issue of BodyShop Business Magazine features a Tech Editorial on the sandpaper used in bodyshops for crash repair. Since Abrasive Resource is one of the suppliers referenced, we are happy to share the article written by Mark Clark here:

"In a well-known auto painter time study, it was determined that those in the paint department spent one-third of their time at work sanding something. Metal shop techs are also frequently abrasively scrubbing away at the vehicle for one reason or another. While sandpaper may be a mundane item, it’s clearly a big part of what happens in collision repair. It is, in fact, a multi-point cutting tool designed to penetrate the substrate and pull the chipped material out of the scratch, leveling the old finish and providing increased surface area to improve the adhesion of the new coatings.

Universal Manufacture

Automotive refinish sandpapers are manufactured all over the world. From Mexico to Portugal to Finland to Canada to the good ol’ USA, numerous manufacturers produce quality goods to expedite the refinishing process.

An educated consumer will understand the basics of something before they can appreciate the features (the unique characteristics of that brand), which lead to the advantages (better than the other choices because…) and finally the benefits (why your job will be easier, faster or better) of any particular brand. I’ll leave it to each vendor to convince you of their features and benefits, but will endeavor to inform you about the construction of automotive grade sandpapers.

From the Bottom Up

All abrasive papers and cloths begin with the backing material, on which is applied the first coat of adhesive, into which the abrasive particles are distributed. After their application, a second coat of adhesive is applied to hold the abrasive minerals upright on the backing and minimize clogging.

The residue from sanding is composed of both the abrasive minerals breaking down into dust and the sanded surface being removed. This mixture is correctly called “swarf.” Think of it this way: wet sanding provides the truest cut because the sheeting water washes the swarf out of the way of the next cut, preventing the clogging of the remaining abrasive minerals with hot, melted filler, primer, paint or clear. With the swarf out of the way, any sandpaper will last longer.

The Backing

Most automotive refinishing sandpaper has a paper backing, although some types use foam or plastic film. Plastic film is an important development for waterborne/low-VOC base-coats, says Anne Knight of Carborundum Abrasives North America.

“Waterborne technology allows for thinner coats of paint, so it’s critical not to cut through them,” said Knight. “So if the substrate is totally flat (like film), then the ‘highs and lows’ of the grains are minimized and you get a more consistent cut, especially when using a tighter grain sizing.”

Heavy-duty abrasives can use a resin fiber backing, which is multiple layers of specially impregnated paper, and still others use cloth in various weights and stiffnesses to back the abrasive minerals.

Ordinary paper and cloth backings use a letter to delineate their thickness, strength and flexibility. By weighing a ream (480 sheets) of 24-inch by 36-inch paper, a weight in pounds is established and a letter is assigned. The lightest weight automotive paper backing is assigned the letter “A,” and heavier weights of thicker papers are rated “B,” “C,” “D,” “E” and “F.” In each case, the backing is made from heavier, thicker and more durable paper.

More durable backing papers are used with more durable and long-lasting abrasive particles. Putting a ceramic abrasive particle on an “A” weight paper would cause the paper to give out before the mineral was exhausted. Likewise, putting an inexpensive silicon carbide particle on “E” weight paper would be foolish, as the paper would outlast the mineral.

However, some manufacturers claim to have gotten around this paper weight-abrasive type issue.

“We offer a B-weight paper that’s reinforced with latex fibers to make it incredibly strong and tear-resistant, and that’s what we put our ceramic grain on…which is an exceedingly durable abrasive,” said Carborundum’s Knight. “Components can be added and formulations can be modified to enhance the strength and characteristic of a backing.”

Cloth backings are commonly used in grinding belts and are rated by their weight and flexibility. “J” weight cloth backing is very flexible and typically used in polishing operations. “X” weight cloth is heavier, stronger and less flexible, and “Y” weight cloth is extra heavy duty and used in the heavy grinding of bare metals.

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Bottom of the Backing

Sandpaper is attached to the power sander or the sanding block in various ways. If the sandpaper is to be manually clipped onto the tool, then nothing but bare paper is on the bottom of the sandpaper. For many years, auto body techs applied glue from a squeeze tube or spray can to both the backing pad on the tool and the bottom side of the sanding disc to attach the sandpaper. This application of disc adhesive was time-consuming (the most expensive thing in any body shop is labor time!), and when a ribbon of glue from the tube wasn’t smeared flat, the paper wore out prematurely on the high spots of attachment glue.

When abrasive manufacturers began to coat the bottom of the sanding discs with pressure-sensitive adhesive (PSA), both the quick attachment times and the lack of high spots were a welcome change. Hook-and-loop attachment systems are not only fast and high-spot free, they run cooler because air can circulate under the sandpaper. Also, the paper can be easily removed and reattached, which is not always possible with many glued attachments. This is useful with 36 to 40 grit papers on airboard or hog sanders because it makes it easy to save and reuse sheets or discs that aren’t worn out.

The First Glue Coat

Correctly called the “make coat,” this adhesive is applied to the top of the paper backing by spraying, brushing or rolling it. It’s often made from animal hide glue or a man-made adhesive resin. When constructing wet-or-dry sandpaper, animal hide glue isn’t a good choice as the water will dissolve the bond and let the abrasive minerals come loose. How the adhesive is made and how it’s applied is one of the many differences in the shop’s cost of sandpapers. More expensive resin bond adhesives and precision application methods make for a sharper-cutting and longer-lasting sandpaper, but cost more than cheaper glues and less accurate application methods.

Abrasive Mineral Type

Some abrasive minerals are found in nature, others are constructed by mixing or synthesizing minerals or resins under high heat. Naturally occurring minerals like emery (fingernail files), garnet (balsawood airplanes) or flint (electronic contact points) are too soft for use in auto refinishing. We need an abrasive grain that’s hard, sharp and durable. Three basic manmade abrasives are used in our business:

Silicon Carbide. Silicon carbide is made from sand and carbon fused together in an electric furnace. It produces an abrasive mineral that fractures easily into sharp wedges. While those multiple sharp edges do a great job cutting, they’re not very durable as they just continue to fracture into smaller and smaller wedges. This is the mineral of choice for fine grit papers.

Aluminum Oxide. Aluminum oxide is a synthetic mineral made from bauxite, coke and iron fused together under varying temperatures; some is heat treated, some is not depending on the application. Its improved hardness fractures in larger chunks, cuts cooler and has a longer life than silicon carbide particles. However, because it cleaves in larger pieces, it doesn’t have as many extra sharp edges.

Ceramic. Ceramic abrasives combine the best of both worlds in that they’re very sharp, very hard, extra durable and run cooler. These particles may contain zirconium dioxide, which, when combined with alumina (used in the production of aluminum metal), creates a very hard particle that fractures in much smaller, sharper chunks. The actual formula for a particular brand’s ceramic abrasive mineral may be proprietary, and the manufacturer may have a specific name for their version. It usually takes more downward pressure on the sander to force the ceramic mineral particle to break down. In any case, these abrasive particles are created under the highest heat from the most sophisticated ingredients and cost the most to produce. Their micro structure won’t cleave or break away, which easily makes them very long-lasting.

As labor time is the most expensive thing in a body shop, any abrasive paper that lasts longer between disc changes will pay for itself quickly. If the cheap paper discs wear out and need to be changed every few minutes and the shop’s door rate is $42 per hour, then every minute the tech wastes changing discs more frequently costs 70 cents. Longer-lasting ceramic discs may quickly recover their additional costs.

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Abrasive Mineral Size

Exactly how big the abrasive crystal is determines the “grit” number assigned to that size. There are three commonly used methods to grade particle size in automotive sandpaper. At 180 grit size, all three method’s particles are the same 0.00304 inches in diameter. Above and below that specific grit, there are slight differences in particle size, depending on which abrasive grading method is used.

ANSI. ANSI (American National Standards Institute) is the grading method most commonly used over the history of our business. With a 16-grit particle the largest and a 3,000-grit particle the smallest, these are the numbers we were raised with. To oversimplify, this method uses something like a kitchen sieve. Put a handful of abrasive particles in the sieve, shake it and everything the size of the sieve hole and smaller falls through, while larger particles remain in the sieve. The trouble with the ANSI system is that as much as 25 percent of the graded particles aren’t the same size. Common sense says that half will be smaller than the sieve hole and half that wiggle through will be larger. These coarser, “wild” grits can cause problems. If your 220 grit paper has some 280 mixed in, no problem. If your 220 paper has some 150 grit mixed in, that’s an issue. The larger particles may have slipped through the sieve sideways or snuck in.

FEPA. FEPA (Federation of European Producers of Abrasive) is a tighter grading system, and more of the particles are the same and uniform in size. You know when this method is used because the grit number is preceded by the letter “P” as P-220 or P-400. A 320 ANSI particle is about the same size as a FEPA P-400 particle. A P-1200 FEPA is about the same size as an ANSI 600.

JIS. JIS (Japanese Industrial Standard) is the tightest grading system commonly used in automotive sandpapers. Virtually all the particles are the exact same size when graded this way. This system uses a tighter grading system with less opportunity for “wild” grit to make it through to the sandpaper. There is no leading-letter indication that this is how the abrasive grains were sized; you would have to be told which system was employed (unlike the FEPA method, which always has the leading “P” before the grit size).

As an aside, grading abrasive particles in microns will produce an extremely uniform grit, as each one is exactly some exact micron in diameter. The problem is that we all know a smaller number is a coarser grit and a larger number is a finer grit (24 = coarse, 400 = finer). In microns, it goes the other way – a smaller number is a finer grit, and a larger number is a coarser grit (715 = coarse, 25 = fine). A confusing change; it’s hard to teach an old dog (or entire industry) a new trick.

Mineral on the Backing

Now with the paper backing weight chosen, the make coat of adhesive applied and the mineral and grit size established, it’s time to stick the abrasive into the glue. The cheapest method is to simply sprinkle the abrasive grains onto the backing, much like applying salt to your food or spreading grass seed by hand from a bucket. In this method, the grit sticks where it lands, and some particles will point up, down or sideways.

More expensive methods use an electrostatic charge to get the minerals to point up and coat the surface evenly. Whether the paper has a negative charge and the minerals a positive charge or the opposite, the minerals are attracted into the glue uniformly. Like every other step so far, more expensive choices make for longer-lasting sandpapers.

How much of the paper’s surface is covered with the abrasive mineral matters as well. When sanding something that will melt (body filler, primer surface, paint), you must have spaces in between the particles for the melted material to lodge momentarily until the next stroke of the sander can spin it out.

All automotive papers are “open coat” abrasives, meaning the minerals don’t cover the surface but rather have empty spaces between them. When grinding bare metal, “closed coat” abrasives are the choice because there are more of them and the bare metal won’t melt under the heat. To illustrate this point, take a painted part over to the bench grinder, which has a closed coat (solid abrasive) grinding wheel on it. Hold the painted part against the spinning wheel, and you’ll see that in moments, the melted paint covers the abrasive particles, clogs the minerals and prevents any more paint from being removed.

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Second Glue Coat

Correctly called the “size coat,” this second application of adhesive has several purposes: to help hold the abrasive minerals upright, with the sharp edge out; as additional glue to physically hold the minerals onto the disc and not be broken off easily; and to help slide the swarf out of the way.

Untreated (no lubricant) sandpapers are often brown in color and could be called “production” paper. Lubricated papers have zinc stearate powder added to the size coat of adhesive and prevent the loading of the papers with swarf. Described as free-cut or no-fill, they last longer than untreated papers because they don’t clog as quickly. Zinc stearate is a slippery soap used in “fanning powder,” which magicians use to make a deck of cards fan out. This soft white powder is also used as a mold release agent to prevent the molded part from sticking to the mold in manufacturing.

One of the things that distinguish sandpaper brands is how well their anti-load lubricant works. Much like the production of ceramic abrasive particles is proprietary and unique to each manufacturer; their particular blend of anti-loading soap is, too. In an effort to distinguish improved versions from cheaper offerings within one brand and certainly between different brands, the manufacturer will add coloring to the final coat to distinguish their version. This is how refinish sandpapers came to be white, yellow, orange, pink, gold, green, blue, red, purple and any other color you might name.

One Among Many

In each case, the sandpaper manufacturer wants their blend of backing weight, adhesive type, mineral construction, particle size, mineral application method and lubricated adhesives to stand out from the other guy’s version. Like anything else in life, you get what you pay for. Lightweight papers, cheaper glues, softer minerals, causal grading systems and minimal lubricants cost less. Heavier backings, better resins, harder minerals, tighter grading and sophisticated lubricants cost more.

A productive body shop recognizes that techs’ labor time is far and away the biggest expenditure. That said, the smart choice is to buy the best, fastest cutting, longest lasting refinish sandpaper available. Your jobber will be happy to explain all the features, advantages and benefits of their brand…now that you know how it’s made!

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Mark Clark is a well-known industry speaker and consultant. He’s celebrating his 23rd year as a contributing editor to BodyShopBusiness. To read this article in the context of the magazine and to access an additional Sandpaper Spec Chart, please visit the BodyShop Business Website!

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Buying Your First Sander

My son is at the age now where he is setting up his first workshop and is ready to move on from always borrowing Dad's tools to owning his own. Recently, ShopNotes ran an article in their "Setting Up Shop" series devoted to buying your first sander--I wish I had written it, because I agree with everything they said!

When it comes to buying your first sander, my suggestion is to get a 5" random orbit sander. This tool provides a good balance of features to tackle all kinds of tasks. And once you get an idea of its capabilities and limitations, you can use that information to guide your decision for buying other sanders.

Because tool models are always changing, I usually hesitate to recommend a certain brand or model. Instead, I like to look for specific features. So here are the things I feel are important in a sander:

The Sanding Pad- The 5" diameter pad is small enough to use one-handed but large enough to keep surfaces level. Another thing I look for is a hook and loop pad. Switching (and reusing) sanding disks is just so much more convenient than pressure sensitive adhesive (PSA) disks. Note: you can buy hook and loop replacement pads for most PSA sanders. Abrasive Resource carries these on our website:
5" Conversion Pads .

Dust Collection- Also high on my list of priorities is dust collection. Some tasks, like flattening a panel, can generate a lot of dust. Keeping it out of the air (and my lungs) is important. Although all sanders come with some kind of filter, I look for sanders that offer easy hook up to a dust collector or shop vacuum.

Comfort- Finally, I look for a sander that feels comfortable. Admittedly, this is the most subjective "feature". You'll need to get your hands on several models to find out which one is a good fit. Some sanders offer two hand positions: a top mounted handle or a center body grip.

Now all that's left is the sanding discs! Abrasive Resource converts discs in any size, grit, backing and vacuum hole pattern in both the self adhesive PSA style, as well as the hook and loop backed discs. Visit our random orbit sanding disc page and give us a call at 800-814-7358 if you have any questions! Sanding Discs from Abrasive Resource

How to Achieve a High Gloss Varnish Finish on your Wood Projects

After sanding your wood piece with a final sand of P220 grit paper, remove the dust using either a vacuum or a tack cloth. Apply a coat of orange shellac and let it dry for 30-45 minutes. Now apply your first coat of varnish and let it dry for 12-24 hours.

If you apply the second coat the next day, there shouldn’t be any need to sand the first coat because the second will bond chemically to the first. If, however, more than a day has gone by since the first coat, the second coat will no longer chemically bond to the first, so you will need to scuff sand the first coat with P220-P320 grit sandpaper to give that second coat a physical bond.

Now it’s time to level the first two coats. After the second coat has dried for at least 24 hours, sand it with P220 grit sandpaper. Sand with the grain, using a rubber or cork sanding block on flat surfaces to keep the pressure uniform. Use your fingers only when you can find nothing else that will work as a sanding block—and switch to P320 grit so that you don’t cut through on edges or details!

As you level the surface, you should reveal a pattern of dull and shiny areas…the dull areas are the high spots being planed down by the abrasive and the shiny areas are the low spots that haven’t been touched. Don’t try to remove all the shiny areas completely, because you may accidently cut through on the edges.

After removing the sanding dust, apply a third coat of varnish. Let it dry for 12 to 24 hours. Now you’ll need to make a judgment call—do you have an unfilled pore pattern showing or do you feel that your first three coats were fairly thin? If so, now is the time to apply a fourth coat directly over the third. Let the fourth coat dry for 48 hours.

Sand this third or fourth coat with P400 grit SC Waterproof sandpaper, again using a sanding block. Lubricate the paper with water, adding a drop or two of dishwashing detergent to prevent clogging. Frequently wipe away the slurry to check your progress. If the varnish is making little balls on the sandpaper, that is an indication that your varnish needs to dry longer—even several days! Look for the same dull/gloss pattern as before, but aim for having fewer shiny areas and a flatter surface. Wipe down the piece with mineral spirits to remove any dried slurry.

For the final coat, thin your varnish with about 15% mineral spirits so that it flows on with virtually no brush marks, filling any hollows. Now let this final coat dry for at least 48 hours—but even longer is better. The harder the finish, the smoother the final result will be!

Now it’s time for your finish sanding. Begin with a light wet sanding in P1000 grit SC Waterproof sandpaper to remove the dust nibs and any small brush marks. If the sandpaper starts clogging, stop sanding and wait another day or two for additional drying of the varnish. Once you are in this final sanding stage, regularly check your progress until 80-90% of the surface is dull. Go light on the edges and small details.

Next, wipe down the piece with a damp sponge and clean water. Repeat the sanding process with sandpaper in P2000 & P3000, being careful to always clean the surface entirely before moving onto the next grit. You should only have a light sprinkling of low, shiny freckles left behind on the flat surfaces. You can continue this process all the way up to a P 5000 grit sandpaper finish if you would like! Finish by rubbing out to the desired sheen with a wax.

You can find all of the sandpaper mentioned in this blog post on Abrasive Resource's Online Store.

Abrasive Resource introduces the new “Big Foot” Sanding System

Abrasive Resource, a leading US converter and distributor of abrasive sanding supplies, is pleased to announce its’ expansion into manufacturing drive pads and custom back-up pads for use on the GEM® Orbital Sander/Polisher. These slip on pads, along with 11 x 5 or 12 x 6 hook and loop sanding discs, make up the Big Foot Sanding System.

Abrasive Resource has served the wood and solid surface markets with sanding discs for over 25 years and the addition of custom back-up pads designed for use on the GEM Industries® Orbital Sander was a natural progression in their offering of abrasive products and supplies. Now, in addition to distributing the popular GEM sander, Abrasive Resource will also provide fabricators and shops with options of an 11” diameter pad with a 5” center hole or a 12” diameter pad with a 6” center hole.

The Big Foot Sanding System allows the sanding pressure to be concentrated on the outside diameter of the back-up pad. This provides a uniform scratch pattern and relieves any loading that may be created in the center of a traditional solid sanding disc. The slip on back up pads are tapered on the edge to enable finishing all of the way up to a back splash. In addition, the 5” or 6” center cut out discs are available with any vacuum hole pattern and are included at no charge to use with a shop’s smaller disc sanders.

To learn more about the “Big Foot” Sanding System, visit www.abrasiveresource.com.

Introductory kits are available in the 11” x 5” size at http://www.abrasiveresource.com/detail_sale115BPDDVKIT__DonutDiscs__Blue_Hook_and_Loop_Sanding_Discs.html .

The 12” x 6” size can be found at http://www.abrasiveresource.com/detail_sale126BPDDVKIT__126bluhookdisc__Blue_Hook_and_Loop_Sanding_Discs.html .

Media Contact:
Debbie Swanson
Abrasive Resource
900 Lund Boulevard #100
Minneapolis, MN 55303
mail@abrasiveresource.com

Choosing the Correct Backing for Your Sandpaper & Abrasive Products

Whether paper, cloth or film, the backing used for coated abrasive products must be smooth enough for a uniform adhesive coating, strong enough to withstand grinding pressures and flexible enough to conform to contours if that is necessary to your application.

Paper: The paper backings used for coated abrasives are highly specialized technical papers made to very exact specifications for abrasive use, thereby assuring certain essential physical properties such as finish, strength, adhesion, flexibility and weight.

Paper weights are determined by the number of pounds in a papermaker's ream of 480 sheets that are 24" x 36" in size. The standard paper weights used in coated abrasives are shown below and are indicated by a letter code which appears immediately after the grit size on the finished product backing. Briefly stated, the lighter the backing, the greater the degree of flexibility and the heavier the backing, the greater resistance to tearing.

• A-weight (40 lbs) -Light and flexible. A weight is primarily used for sheet products used on hand sanding operations in grits 80 and finer.
• C-weight (70 lbs) -Stronger and less flexible than A weight. This backing is chosen for hand sanding and for use on small, portable power sanders. Used for intermediate sanding in grits 36 through 80.
• D-weight (90 lbs) -Stronger and less flexible than C weight. This backing is also used for hand sanding and small, portable power sanders on coarse and intermediate grits 24-80.
• E-weight (130 lbs) -Stronger and less flexible than D-weight, this backing is primarily used on roll, belt and disc applications where high resistance to tearing is needed.
• F-weight (165 lbs) -The strongest, least flexible paper backing utilized. Used primarily for heavy-duty sanding discs, sheet goods and sanding belts used in the floor sanding market and paper wide belts used in woodworking applications.
  

Cloth: Cloth backings are more durable than paper, offer greater resistance to tearing, and tolerate continual bending and flexing during use. The cloth used for abrasive backings are manufactured in the traditional way most cloth is processed--by interlacing threads running at 90' angles with each other. The friction at the numerous points of intersection hold the fabric together. Cloth used for abrasive backings often requires desizing, shrinking, drying, stretching, filling and calendering in order to produce the desired strength, flexibility and coating surface.

The standard cloth weights used in coated abrasives are also indicated by a letter code which appears immediately after the grit size on the finished product backing.

• J-weight (Jeans) -The lightest and most flexible cloth backing, this backing is used where finish and uniformity of surface are more important than stock removal. Most often seen on abrasive shop/utility rolls, cloth sheets and sanding belts. Ideal for finishing, blending and where considerable flexibility and conformity are required, such as contour work on curved surfaces.
• X-weight (Drills) -Stronger and stiffer than J-weight, this backing is used on a multitude of abrasive products from coarse grit stock removal through fine grit finishing and polishing. Consistent productivity, good finishes and long product life are characteristics of abrasive products made on an x-weight backing such as sanding belts and cloth sanding discs.
• Y-weight (Heavy Duty) -The strongest cloth backing utilized, this backing is used on coarse grit products designed for extreme pressure and heavy stock removal operations. Used most often in heavy duty, long life premium abrasive belt materials.

Polyester Film: Polyester based film backings offer special properties that lend themselves to specialized sanding applications. Film backed abrasives offer thicknesses having ultra tight tolerances...which is important for the electronics, fiber optics and surgical instrument/medical applications. The benefits of a film backed abrasive product is now also being realized in the automotive and solid surface markets.