# Scratches between coats of varnish



## mhughes81 (Feb 21, 2012)

Hi Quick question. I'm dry sanding with 400 grit sandpaper between coats of wiping varnish and noticed that I'm getting scratches showing up. I though the next coat would cover them up but they're coming through the finish. Anyone have ideas for a solution? I suppose I could try using #0000 steel wool or wet sanding or going up to a higher grit, but I'd rather avoid the mess of wet sanding. Any ideas? Thanks!


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## chemmy (Dec 13, 2011)

mhughes81 said:


> Hi Quick question. I'm dry sanding with 400 grit sandpaper between coats of wiping varnish and noticed that I'm getting scratches showing up. I though the next coat would cover them up but they're coming through the finish. Anyone have ideas for a solution? I suppose I could try using #0000 steel wool or wet sanding or going up to a higher grit, but I'd rather avoid the mess of wet sanding. Any ideas? Thanks!


Usually if scratches are showing between coats its caused by the sanded coat not being cured enough yet and lays the scratch open wider than what the sanding medium itself would normally do. try allowing twice as long or longer for the varnish to dry and then try it again and see what the results are ok?:yes:

PS: if you provide pics it would help greatly to be able to see exactly what is happening ok, guesses are cheap, visuals narrow things down!!


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## Dominick (May 2, 2011)

+1 agree, also lightly sand in between coats.


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## MNsawyergp (Jan 31, 2012)

Keep an eye on your sandpaper. It will get little globs on it as you sand the finish. Either get a new piece or pick them off. These globs will scratch the finish and you will see it in the next coat.


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## HowardAcheson (Nov 25, 2011)

Are you sanding in the direction of the grain only?


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## cabinetman (Jul 5, 2007)

MNsawyergp said:


> Keep an eye on your sandpaper. It will get little globs on it as you sand the finish. Either get a new piece or pick them off. These globs will scratch the finish and you will see it in the next coat.


+1. :yes: A good possibility. If the sanding was done dry, the sandpaper would get grabby and gummy if the finish wasn't dry enough.










 







.


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## mhughes81 (Feb 21, 2012)

Good suggestions... I'm making sure the paper is not gummy, but I'll take the advice and let it dry for 16-24 hours. Yeah i was sanding also across the grain, which made the scratches more prounounced. Also, am I supposed to "scuff sand" by hand, or use a block? A block seem like it would level the surface better but i also noticed that's where the sandpaper gums up a bit more.

Thanks!


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## chemmy (Dec 13, 2011)

mhughes81 said:


> Good suggestions... I'm making sure the paper is not gummy, but I'll take the advice and let it dry for 16-24 hours. Yeah i was sanding also across the grain, which made the scratches more prounounced. Also, am I supposed to "scuff sand" by hand, or use a block? A block seem like it would level the surface better but i also noticed that's where the sandpaper gums up a bit more.
> 
> Thanks!


If the finish is gumming its still to fresh, with a thurougly dry surface it will not do that, use it as an indicator in the future. :smile:


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## MNsawyergp (Jan 31, 2012)

The way I know whether the finish is ready to sand is when I go over the surface with the wet and dry 400 grit, a nice powder is created. Everything feels bone dry. If there is any resistance between the sandpaper and the finish surface, it is not ready. I use a sponge, not a dried out crusty one, but a nice flexible rectangle shaped sponge as a sanding block. It doesn't have a sharp edge and won't create a pressure point as you sand out the finish.


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## HowardAcheson (Nov 25, 2011)

>>>> am I supposed to "scuff sand" by hand, or use a block?

Flat surface should be scuff sanded with your paper on a flat felt or rubber surfaced sanding block. Sand in the direction of the grain. Making and keeping a surface perfectly flat gives a much nicer final appearance. Avoid steel wool or a non-woven abrasive pad for flat surfaces. These abrasives just ride up and down over non-flat surfaces without flattening them. Use these abrasives for curved surfaces. Flatness is goodness.

As a number have said, you must let the finish dry to the point where sanding results in a powder.


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## Tony B (Jul 30, 2008)

If you are still showing scratches through the 400 grit, consider this:
You may not have completely sanded out the scratch patterns of the previous grits before you worked your way up to 400. 
In essence, you may have jumped grits too soon. Some of the scratches you are seeing could be from 120 grit that was not completely sanded out when you jumped up to the next grit.
If that is the case, it will be many coats before the old 'scratches' will be completely filled in.


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