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finishing question - fingerprints

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Forum topic by depictureboy posted 02-16-2011 08:30 PM 2045 views 1 time favorited 6 replies Add to Favorites Watch
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depictureboy

420 posts in 3104 days


02-16-2011 08:30 PM

I am working on finishing the doors for my bedroom project, i have been working on rubbing out the center panel as it will be glossy compared to the actual door frame, I have them very smooth now, but I notice that if I put my finger on it with any sort of pressure it leaves a fingerprint in the finish…

I am using zinnser shellac(the dewaxed sanding sealer) as my topcoats, and this is the first time i have noticed this issue. Maybe its because its so polished and smooth. I am using mineral spirits as my cutting agent with the wet/dry sand paper…But I have noticed that the rails and stiles are also doing the same thing, even if I let the item sit for a day or so inside to really harden the finish…

Is there something I am not getting or is shellac really that soft all the time?

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.


6 replies so far

View ScienceNerd's profile

ScienceNerd

24 posts in 2487 days


#1 posted 02-16-2011 08:37 PM

Are the fingerprints in or on the finish? (I’m guessing the former, but let’s make sure before diagnosing. :)) In my experience, shellac should harden up nicely without showing prints. If it’s not a time-sensitive project, you might try letting the finish set up for several days and see if it cures properly…probably a good idea anyway before rubbing it out, in general.

If that does not fix things, I’ll defer to the finishing experts here. Can time/temperature make shellac go soft in the can?

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depictureboy

420 posts in 3104 days


#2 posted 02-16-2011 09:53 PM

yea, Im thinking that its actually making indentations, cause they wont buff out easily. I am using mineral spirits for which should be ok, but maybe its not…or maybe my skin is reactive hehe

btw…i tested on project parts that have set a few days, and its still doing it..

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.

View ChrisForthofer's profile

ChrisForthofer

150 posts in 2529 days


#3 posted 02-16-2011 10:07 PM

I havent used shelac a ton but isnt, denatured alcohol the solvent for shelac not mineral spirits? I am assuming you are attempting a french polish type effect on the panel? I have never read anything dealing with shelac that called for mineral spirits. Just good old Denatured Alcohol. I might be out in the weeds on this one though.

Found this:

http://www.rustoleumibg.com/images/tds/CBG_ZIN_TDS_BULLS%20EYE%20SEALCOAT%20Universal%20Sanding%20Sealer_2010.pdf

The instructions recommend alcohol for thinning.

Chris.

-- -Director of slipshod craftsmanship and attention deficit woodworking

View hObOmOnk's profile

hObOmOnk

1381 posts in 3589 days


#4 posted 02-16-2011 10:11 PM

If the shellac has completely dried and the finish is soft to the touch then you are probably using spoiled shellac.
Spoiled shellac that has esterified in the can will not be completely hard after the alcohol dries.

Test the shellac by brushing a little on to a piece of glass. Let it dry for a couple of hours then test it with a fingernail. If it indents or is soft and gummy, then it has gone bad. You can also very carefully sniff the wet shellac. If it is esterified it will have a distinctive fruity smell.

If your shellac finish is bad, you’ll need to strip it with alcohol and start over with fresh shellac.

-- 温故知新

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fussy

980 posts in 2513 days


#5 posted 02-16-2011 10:24 PM

Hobomonk has your problem nailed. It is not uncommon to find old shellac on the shelves in some stores (ever buy old milk?). He also nailed your solution; sorry. BTW, using mineral spirits as a sanding lubricant is ok, but water with a drop of dishashing detergent would work too.

Steve

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View depictureboy's profile

depictureboy

420 posts in 3104 days


#6 posted 02-17-2011 01:37 AM

I was using water to do the sanding, but with the way my panels are setup it makes a heck of a mess and I am worried about it getting in my actual frames, I switched to mineral spirits so that if it does get into my grooves there wont be as much to worry about.

I did some experimenting when I got home, it seems that maybe its a combination of nerves and perhaps optics…i put my thumb to the middle of the panel and laid down a print, but it buffed out easily. Mostly I am having the issue when I am doing the wet sanding so maybe its just an illusion with all the spirits and wetness going on…i never let it dry to see what it really looked like afterwards…though I did find sanding dust on my panels tonite and was surprised..eheh

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.

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