# Urethane over Shellac



## woodgauy78 (Feb 24, 2012)

I have two coats of shellac over Watco oil and would now like to finish off with a matte like finish. I understand that oil-based polyurethane should not be used over shellac.
I have very little experience with shellac as a finish coat but rather as a sealer. Any suggestions would be appreciated. Thanks guys, Mark


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## chemmy (Dec 13, 2011)

woodguy78 said:


> I have two coats of shellac over Watco oil and would now like to finish off with a matte like finish. I understand that oil-based polyurethane should not be used over shellac.
> I have very little experience with shellac as a finish coat but rather as a sealer. Any suggestions would be appreciated. Thanks guys, Mark


If your shellac coat contains any "wax", then no, oil modified poly's like minwax and others will not adhere. You can however use Varnishes, either interior types or exterior types. They can be phenolic oil or natural resin oil, short or long. If you did use wax containing shellac, you can apply another coat of Zinsser "sealcoat" shellac, which is wax free, over what you have and then apply oil modified poly over it. Be sure to sand back the shellac coats you have applied first though so you donot over build with shellac, it is really meant as a first coat only material - unless your finishing with shellac only.

Always test on samples before applying to actual project ok?:yes:


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## woodgauy78 (Feb 24, 2012)

chemmy said:


> If your shellac coat contains any "wax", then no, oil modified poly's like minwax and others will not adhere. You can however use Varnishes, either interior types or exterior types. They can be phenolic oil or natural resin oil, short or long. If you did use wax containing shellac, you can apply another coat of Zinsser "sealcoat" shellac, which is wax free, over what you have and then apply oil modified poly over it. Be sure to sand back the shellac coats you have applied first though so you donot over build with shellac, it is really meant as a first coat only material - unless your finishing with shellac only.
> 
> Always test on samples before applying to actual project ok?:yes:


Thanks chemmy, that's great advise. Hard to believe that I could be in the shop over 60 years and not have the answer for that question, isn't it. Now I see why your name keeps showing up when we need help. Well done!


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## cabinetman (Jul 5, 2007)

woodguy78 said:


> I have two coats of shellac over Watco oil and would now like to finish off with a matte like finish. I understand that oil-based polyurethane should not be used over shellac.
> I have very little experience with shellac as a finish coat but rather as a sealer. Any suggestions would be appreciated. Thanks guys, Mark


 





 

The Watco you used was not likely just a pure oil. If the label reads with "Finish" on it, it's likely a varnish, oil, solvent mix. For example...Watco Teak Oil "Finish", or Watco Danish Oil "Finish". It by itself is a stand alone finish. That could have been the only finish to apply. It would need no barrier coat (shellac) to apply oil based polyurethane over it. 












 







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## chemmy (Dec 13, 2011)

woodguy78 said:


> Thanks chemmy, that's great advise. Hard to believe that I could be in the shop over 60 years and not have the answer for that question, isn't it. Now I see why your name keeps showing up when we need help. Well done!


That's why i participate WG, thanks.:thumbsup:


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## woodgauy78 (Feb 24, 2012)

I usually prefer an "oil" finish myself but I'm finishing up the cherry Shaker Tall Clock seen in PWW Aug. '07 and I wanted to age it some by glazing as sugzgested by the plans. So shellaced, glazed and another coat of shellac bringing me to where I am now. Oh yes, many samples, trials and errors have lead me to what I have now which is good. I want a flat or matte finish so I'm trying to decide. Maybe I should conclude with my favorite paste wax finish. What do you think?


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## chemmy (Dec 13, 2011)

woodguy78 said:


> I usually prefer an "oil" finish myself but I'm finishing up the cherry Shaker Tall Clock seen in PWW Aug. '07 and I wanted to age it some by glazing as sugzgested by the plans. So shellaced, glazed and another coat of shellac bringing me to where I am now. Oh yes, many samples, trials and errors have lead me to what I have now which is good. I want a flat or matte finish so I'm trying to decide. Maybe I should conclude with my favorite paste wax finish. What do you think?


Of course it's strictly your choice as to the wax, but it kind of goes against what your saying your wanting to acheive as far as a "flat or matt" look ? Even if steelwooled, wax will not give such a low sheen, not even with G. Franks can you do such, I personally can only do it when using nothing but specialty waxes i make myself on the "bare" wood, not over a finish of any gloss like shellac. So please explain to me what it is your seeking by using it over shellac or possibly a flat poly, etc.?:huh:


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## woodgauy78 (Feb 24, 2012)

chemmy said:


> Of course it's strictly your choice as to the wax, but it kind of goes against what your saying your wanting to acheive as far as a "flat or matt" look ? Even if steelwooled, wax will not give such a low sheen, not even with G. Franks can you do such, I personally can only do it when using nothing but specialty waxes i make myself on the "bare" wood, not over a finish of any gloss like shellac. So please explain to me what it is your seeking by using it over shellac or possibly a flat poly, etc.?:huh:


I just got through a long note to you Chemmy and lost it in the send. I'm new here. Let me try again but more briefly. After the second coat of shellac I dulled it down with 0000 steel wool and liked the result. On one of my sample peices, I tried a light coat of wax and liked it even better. (you make your own? does chemmy stand for chemist?) No, not matte or flat but appealing so I think I have found my answer. I really appreciate your help and would like to ask one more question re: your last reply. You mentioned G. Franks. One more thing I'm not familiar with. Help!
Wish you had. een my neighbor for the last few decades.


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## chemmy (Dec 13, 2011)

woodguy78 said:


> I just got through a long note to you Chemmy and lost it in the send. I'm new here. Let me try again but more briefly. After the second coat of shellac I dulled it down with 0000 steel wool and liked the result. On one of my sample peices, I tried a light coat of wax and liked it even better. (you make your own? does chemmy stand for chemist?) No, not matte or flat but appealing so I think I have found my answer. I really appreciate your help and would like to ask one more question re: your last reply. You mentioned G. Franks. One more thing I'm not familiar with. Help!
> Wish you had. een my neighbor for the last few decades.


Sorry, that should have been George Frank's book where he has a formula for water wax emulsion that gives a delicate but lower sheen appearence to the surfaces applied. Trouble is, that it is "delicate" if polished over a short time it once again starts getting a higher sheen, fine for museum pieces that dont get frequently handled, but not for home useage.

Retired coatings chemist and practioner, 3 generation.


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