Cleaning gunk off of sandpaper

[scsmith42]

I made an interesting discovery today, which everybody else probably already knows...

Whenever I use a sanding sealer (shellac), and do the sanding between coats, I typically use a small electric sander that takes rectangular sandpaper. Unfortunately, the shellac leaves some gummy deposits on the sandpaper within a few minutes, which requires several sheet changes while sanding.

Today I filled a large glass jar with denatured alcohol, and stuck the sandpaper pieces in the jar as they started gumming up. Within a few minutes, the shellac deposits were gone and the paper was not damaged.

I'll probably try hand sanding on the next coat (which may not gum up the paper), the the electric sure is nice for the speed.

 

[ScottM]

Scott I am assuming you are using a quality cloth backed sand paper and not the craft paper backed stuff the BORGs sell.

 

[froglips]

I'd hasten to say you might be melting the shellac with the heat.

While I'd lean towards unpowered hand sanding, another thought would be as light a touch as possible when using a powered sander. Also, you might try open coat garnet paper as opposed to an aluminum oxide paper. Garnet is more friable as I understand it, which is more desirable when sanding finishes.

At least, thats how I understand sandpaper on this day, at this time. This limited time accuracy warranty is in effect for the duration of a piece of pie sitting on a plate on my counter.

Never heard of soaking the paper, thats a great idea.

Jim

 

[Tarhead]

Have to give this a try. I've pretty much switched to steel wool and grey woven pads as no matter how light a touch with the paper I get corns. Sometimes with one pass. Even got a bunch of Stearate impregnated paper from Klingspor and no improvement. Good idea Scott!

 

[Tarhead]

Oh...to address Jim's comment: I get corns using a hand sanding block.

 

[froglips]

Mark, why are you sanding corn?

:rotflm:

Jim

 

[Bas]

Mark, why are you sanding corn?

:rotflm:

Jim

How do you think popcorn ceilings were invented?

Scott - great tip. I had heard of cleaning drum sander rolls in water/ simple green, but not soaking sandpaper in alcohol. Of course, I assume you're using that fancy expensive Festool paper...

 

[Howard Acheson]

If the shellac is corning, it's generally an indication that it has not fully dried. Depending on the age of the shellac, it can take a couple of days to fully dry. 24 hours is normal. Also, the heat of the sanding can "melt" the shellac.

When it's all said and done, I have to ask why you are using a shellac "sanding sealer". A thinned coat of your intended finish will actually work better and you will have no compatibility problems. Even if you elect to use a shellac, more than a single coat is a waste of material unless you are going for a shellac finish.

 

[scsmith42]

If the shellac is corning, it's generally an indication that it has not fully dried. Depending on the age of the shellac, it can take a couple of days to fully dry. 24 hours is normal. Also, the heat of the sanding can "melt" the shellac.

When it's all said and done, I have to ask why you are using a shellac "sanding sealer". A thinned coat of your intended finish will actually work better and you will have no compatibility problems. Even if you elect to use a shellac, more than a single coat is a waste of material unless you are going for a shellac finish.

Howard (and everybody), thanks much for the insight. I'm probably sanding a bit early (less than 24 hours). I'm working with oak, and two of the books that I've read (Finishes and Finishing Techniques by FWW, and Understanding Wood Finishing by Bob Flexner) have recommended using a shellac based sanding sealer immediately after a stain, and then follow it by several topcoats of my final finish. I've been using a water based poly (sold for hardwood flooring) as my final finish, and the sanding sealer for the initial coat right after the stain.

The applications are not fine furniture, but rather various shop shelves, cabinets, counter tops, etc.

ScottM and Bas: Yes, it's a cloth backed paper (Festool). It's the only Festool product that I owned that survived the shop fire - everything else was one big blog of plastic and aluminum...