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finding sander marks?

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Forum topic by Peter5 posted 01-07-2011 06:51 PM 1616 views 0 times favorited 13 replies Add to Favorites Watch
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Peter5

65 posts in 2270 days


01-07-2011 06:51 PM

Hello fellow lumber jocks, you know how sometimes you think you’re done sanding only to apply a finish and the finish reveals sander marks that you didn’t see before? Does anyone know a trick to revealing these marks before applying precious finish? I’m building a table top out of solid cherry right now and it looks good but I know there are sander marks that I’m not seeing in my fluorescent lights. If I rub water over the surface, would that do the trick? Please advise, thanks!

-- Pete, Long Beach, CA http://www.petedeeblefurniture.com


13 replies so far

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lew

11344 posts in 3221 days


#1 posted 01-07-2011 06:55 PM

Wipe the surface with mineral spirits or alcohol

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

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tbone

273 posts in 3150 days


#2 posted 01-07-2011 06:56 PM

Try rubbing a solvent on there. As you know, the water will raise the grain. You also might try laying a shop light right on the surface of the wood. Sometimes the low angle of the light will cast a shadow of an offending scratch.

-- Kinky Friedman: "The first thing I'll do if I'm elected is demand a recount."

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Peter5

65 posts in 2270 days


#3 posted 01-07-2011 07:06 PM

The only solvent I have in my shop right now is acetone- will that work?

-- Pete, Long Beach, CA http://www.petedeeblefurniture.com

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tbone

273 posts in 3150 days


#4 posted 01-07-2011 07:26 PM

Yep. Acetone will do nicely. It evaporates fast, so put your fast eyeballs on.

-- Kinky Friedman: "The first thing I'll do if I'm elected is demand a recount."

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richgreer

4541 posts in 2541 days


#5 posted 01-07-2011 07:31 PM

If I am working on a flat surface on an important piece, I have been using a card scraper instead of sanding. Once you figure out how to use them (and how to sharpen them), they are great and they leave no sanding marks. In my opinion, they leave the surface about as smooth as you would get if you sanded to 320.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

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Loren

8313 posts in 3114 days


#6 posted 01-07-2011 08:10 PM

Wiping the surface with mineral spirits or other non-water solvent
helps to see some stuff. You can also play a light over the surface
at a low angle.

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Peter5

65 posts in 2270 days


#7 posted 01-07-2011 08:32 PM

Awesome, thanks everyone. I’ll try the acetone/light combo today and see how it goes. Hey Rich, what is a card scraper exactly? Could you give me a link to a picture of one? Is it like a block plane? It sounds awesome.

-- Pete, Long Beach, CA http://www.petedeeblefurniture.com

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richgreer

4541 posts in 2541 days


#8 posted 01-07-2011 09:56 PM

If you just search “card scraper” on this website you will find a lot of discussion and some helpful suggestions.

This is probably one of the better ones – -http://lumberjocks.com/toddc/blog/6753

For the record, I don’t completely agree with what is said at this location. In particular, I disagree with his technique for sharpening. Nonetheless, this site and others should teach you a lot.

I’m sure that if you looked hard enough you could find a video on the subject – - if not here I am pretty certain you would find one at the Fine Woodworking site (my second favorite website).

It’s hard to see in the pictures and almost impossible to explain but a board that has been smoothed with a card scraper looks a little different (better) than a board that has been sanded. A card sander cleanly cuts the wood fibers. A sander wears it down with an abrasive.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View ND2ELK's profile

ND2ELK

13495 posts in 3240 days


#9 posted 01-07-2011 10:24 PM

Plat scrapers are good to remove sander marks and scratches after you find them. Mineral spirits works but it also raises the grain and I have seen it cause blotching. What I use to check a piece when I am done sanding, is a clip on light (60-75watt bulb) with a metal hood on it. Blow off piece and hold the light close to the work (4-6”) at a angle. The bright light picks up the sander marks, scratches and glue marks you might not see with out it. Greatest QC tool I had in the sanding department.

-- Mc Bridge Cabinets, Iowa

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Steven H

1117 posts in 2526 days


#10 posted 01-09-2011 03:46 AM

You can look at an angle to see it. But make sure you have good lighting.

View Lee Barker's profile

Lee Barker

2170 posts in 2316 days


#11 posted 01-09-2011 06:59 AM

+1 on the low angle light. I have one of those imported yellow-pipe single bulb halogen lights mounted on a board so I can tip it up and down. I also wired a switch into it, and it lives right beside my downdraft table. Very useful, and always there.

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View BTKS's profile

BTKS

1984 posts in 2930 days


#12 posted 01-11-2011 02:32 AM

Great thread.
richgreer: thanks for the link! I’ve been messing with scrapers for awhile now and have inconsistent results.

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

View Earlextech's profile

Earlextech

1159 posts in 2157 days


#13 posted 01-13-2011 05:48 PM

Avoiding this problem to begin with is the way to go. Scrapers work great either as primary sanders or as follow up after initial sanding. I always apply a coat of water to purposely raise the grain after sanding to 320. Then I use a scaper to finish it out.

-- Sam Hamory - The project is never finished until its "Finished"!

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