#1
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Nitro over shellac
Hi all,
I am just about to start the finish process of a guitar that I built. I will finish it with nitro, but I thought about using shellac as a sealer first, mostly on the top because I like the color that it adds to the spruce. I know you can spray nitro over shellac with no problem, but when I have applied shellac before I have always used a lubricant oil (just a few drops) to the cloth. Will this little of oil cause any problem later with the nitro? I normally finish the top, then remove the finish where the bridge goes, then glue the bridge on it. Can the shellac + lubricant oil applied be a problem for gluing the bridge later? Thanks in advance,
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Jorge |
#2
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I only buy de-waxed shellac. For a seal coat(s) I use a 1 pound/gallon mix without oil. You just want a continuous barrier coat.
Only use oil if you are finishing with French-polished shellac. Under the bridge you will be removing down to the wood so all oil should be gone. I always wipe the surface with naphtha before gluing. |
#3
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If you are spraying the nitro, then just spray the shellac, at about a 1.5-2 lb. cut.
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"Still a man hears what he wants to hear, and disregards the rest." --Paul Simon |
#4
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It should not be an issue for gluing the bridge since you are scraping the finish down to wood but I would hesitate to use oil for a seal coat of shellac. If you must pad it on then do it dry and just make long straight strokes. When I seal with shellac I make a dilute solution and brush it on with a good Hake brush.
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#5
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Thanks for all your replies! They are very heplful.
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Jorge |
#6
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This brings up a question: who masks off most of the bridge area with tape vs scraping entirely after finishing? I’ve always done the latter bc bridge placement can move a mm here or there, so I figure out where it belongs, scribe, and place, but I’m considering doing a smaller area that falls within the overall bridge boundaries that reduces the amount of footprint to scrape.
Thoughts? |
#7
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Limited experience but...
On the guitars I’ve finished to date I masked off around the unglued bridge precisely, then made a Sellotape mask of the bridge footprint. With this Sellotape mask in place the surrounding tape can be removed leaving just the Sellotape. This gives very clean results when French polishing. Not so sure about other finishing methods.
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#8
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Quote:
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#9
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For those of us not in the UK: https://en.wikipedia.org/wiki/Sellotape. It appears to be what we'd call "Scotch tape".
Although I have yet to try it, a while back, someone here suggested using Frisket film, suggesting that it worked very well: https://www.grafixarts.com/products/frisket-film/ |
#10
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Thanks Charles...
I forgot these things have different names across the pond.
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#11
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In theory nitro over shellac violates the painter's rule of 'fat over lean'. Shellac is a softer and more flexible coating than nitro, and this can cause crazing as the nitro tries to hold onto the softer substrate. Many people get away with this, but I have seen instances where they didn't. Keep the shellac layer thin.
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