Cloth Versus Paper Sanding Belts

      Cloth belts are washable and last longer, but may mark the wood more than paper belts. Here's a detailed look at all the pros and cons. January 12, 2015

I'm just about at the end of my supply of 150 grit belts that came with my widebelt when I bought it about two years ago so will have to buy some new ones soon. The local sales rep is trying to sell me on cloth belts saying they'll last at least twice as long as paper? I've only run paper in this grit range and I have several cloth in coarser grits but I don't run enough material to have noticed any difference? So is there any real benefit to spending more for a cloth belt? I run a bit of everything through the machine in terms of type of work, though almost entirely hardwoods. I'm running a single head machine with what I'd guess is a medium plus/minus rubber drum - no platen.

Forum Responses
(Solid Wood Machining Forum)
From contributor G:
My experience has been to use paper backed only on my final grit, which is typically 180 for me. The cloth definitely lasts longer, plus you can clean them with solutions made for this. The down side is the splice is thicker and will leave a slight divot every time it comes around. It's slight, but I notice it. Paper being thinner does a better job for the final pass.

From contributor J:
We run all cloth belts from 3M and usually clean them once or twice before discarding. We had excessive chatter with another brand as the butt splice was slightly thicker than the rest of the belt. The 3M belts have diminished thickness at the splice to account for the adhesive film thickness. It has reduced subsequent finish sanding substantially.

From contributor B:
How are you cleaning the belts?

From the original questioner
Contributor B - not sure if your question was directed towards me, but I don't clean mine. I run them until they seem to have lost their bite and then it's time to replace. I'd be curious as to how guys clean them as well?

From contributor F:
We run 36-80 grit in cloth and 80-220 grit in paper. If we wash cloth we stick them over a 45 gal. drum and spray them that way at the car wash and use soap. We only do this for very coarse belts.

From contributor J:
We have a metal rack set up outside for cleaning belts and an adjacent rack for hanging them to dry. We use a concentrate called "Renuzit" mixed 50/50 with water, applied with a spray gun, scrubbed with a brush and rinsed with a hose. It takes 15-20 minutes per belt and requires some judgment as to whether the belt is worth cleaning. Pine resin, for instance, comes off easily and allows for reuse of an otherwise sharp belt that is fouled. It's a pain, but at $60/hour and $40-45/belt it seems worthwhile. I'd like to know if anyone is aware of a belt cleaning service.

From Contributor A:
I haven't used cloth but when I got my machine I talked to a few reliable sources and they all recommended paper for the best finish. I tried a few brands and settled on VSM from Wurth. I pay about $45.00 a belt. They have a butt splice so don't leave much of a mark. When I looked into cloth belts they were a lot more money so while you can clean them I'm not sure you really come out ahead and cleaning seems like quite a bit of work.

From contributor G:
Actually, it's quite easy and you get a lot more mileage out of a belt. I just use one of those two quart sprayers like you see at the big box stores. Fill it with belt solution, take the belt outside, spray thoroughly, wait five-ten minutes and use a hose to wash it off. They look brand new once done and can be done two or three times. Like I said previously, for the final pass you want a paper belt, all others cloth all the way.

From Contributor E:
As far as cleaning cloth belts, I buy a product from the dollar store called awesome and spray my belts, let it soak in, then rinse with the hose. The results are amazing. I also soak my saw blades in it to clean the pitch from them (the bottom of a five gal pail works great for a 10" blade).

From Contributor A:
Now I'm tempted to try cloth belts in coarser grits. I'm wondering if it throws of your calibration if you use a mixture of cloth and paper? My Butfering has a small block that you turn to different positions to change the roller height to account for the different thicknesses of different grits but if the backing thickness is changing will my readout be correct with the different belts?

From contributor J:
What is the reasoning behind using paper backed abrasives rather than cloth for finer grits?

From contributor F:
Paper belts are thinner so the splice joints in the belts create less chatter marks. They cost less money as well. This of course depends on the quality of the belts you are using.

From contributor V:
To add to the conversation paper belts offer a higher quality fine finish than cloth due to the fact that they run cooler and offer a flatter, more stable medium for the abrasive grit to adhere to. That doesn't mean, however, that they are the best choice for everyone. If our customers run a small shop or have a wide belt sander which requires the belt to be switched out to a different grit before it is used fully to use a finer grade in a sanding sequence, then we recommend cloth belts because they are more durable and less subject to damage by the frequent handling. Most of our larger, production woodworking customers switch to paper belts for 150, 180 and 220 grits.

From contributor J:
Thanks for that explanation. Given that we typically do swap out belts frequently on our single head machine it sounds like we should stick with cloth backing. For what it's worth, we use 3M belts spec'd as 341 D, X weight cloth, closed coat, resin bonded for fine sanding. They have a tape backed interlocking finger type joint, and the ends seem to be thinned so that the splice is no thicker than the rest of the belt. This reduces chatter to the point that it can be pretty much eliminated by the platen. Prior to these belts we were doing a lot of extra finish sanding because the splices were thicker by a couple thousandths on another supplier's belts.

From Contributor W

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This is a big question that there have been a lot of good answers. I have been switching people to more and more paper belts for over a decade, but it isn't right for everyone. If you are switching belts all the time, then by all means, stick with cloth. Paper has a flatter substrate. This means the grain height is much truer over the whole surface. Cloth gives much more highs and lows, so the finish is not as good. This also gives the impression that the belt is lasting longer as you wear down the high spots to get to newer grain in the lower spots. Cloth belts do not out last paper, period. Not if they are being used correctly. Paper cuts cooler, requires less load to cut, and causes less wear on the drums and platens than cloth. I can introduce you to a machine in southern California that runs paper 80,100,120,150 that at one point was running 40,000 cabinet doors a month removing .030". This is on one set of belts a month. They never burn anything and they don't even open the machine for that month. I just set up a good friend with our new paper belts and was disappointed that he only got 15 to 20,000 parts in three straight weeks with 100,120,150, 180 in paper. If he will let me switch the first belt for an 80 grit he will not see a single solitary extra scratch on the part and he will get up to a month on that machine. Paper rules once you get out of the realm of switching belts and sloppy operators.

From Contributor W

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As a sandpaper guy, I must address the cleaning of belts. When you use a wide belt to sand hard wood, you wear the grain. If you wear the grain to the point that the belt starts developing heat and it starts to load up, the belt is now damaging every piece of wood you sand. Heat and pressure are the enemies of sanding. Dull belts cause heat and pressure that compacts the surface of the wood and causes the subsequent operations to remove a lot more than just a clean scratch pattern. You have to grind away the compressed surface to even take out the cross grain scratches. Plus you cannot orbital sand a compressed surface without leaving orbital marks like crazy. You are peeling up wood from a somewhat flat area and it really catches stain well.

The only time it is a good idea to clean belts is if you are running very soft pine that gums up your belts. Then the grain in the belt is not dull, but only covered up. Cleaning works fine for that. For a long time a company was making a dry ice sand blasting machine to clean belts inside of the sander. One of my customers was using the machine until the day I showed up with my digital thermometer. Every time he hit the belt with the blaster the belt became more dull and the heat on the part went up. He never used it again. One hour of training would teach your workers how not to over load the belts on each pass, and you can use the belts for a very long time without damaging the grain or heating up the wood. Then you just throw them away when you are done, with a much better finish the whole time. Using damaged, dull belts will waste more than the cost of the belt in wasted hand sanding time every single week - even more in the reworks due to color matching issues spawned by heat and compression.

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