# 2 Q: Shellac over wb poly, adhesion



## mixer440 (Oct 24, 2009)

Can dewaxed shellac go on top of water based poly ?

second question that has baffled me for years...............


Let's say you're finishing a piece and you completed half the project with water based poly (or oil based poly for that matter). Then you let it dry.

Now when you go back to complete the job you just need to put the poly on just the final areas of the piece........but you will probably overlap a bit here and there onto previous finished poly. 

Dilemma: Supposedly, you're supposed to rough things up a bit, but you don't want to do that to the finished parts or you'd never get done+many times the parts aren't discreet beginnings and endings.


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## Steve Neul (Sep 2, 2011)

mixer440 said:


> Can dewaxed shellac go on top of water based poly ?
> 
> second question that has baffled me for years...............
> 
> ...


Yes you can put sealcoat over water based poly. The surface should be scuff sanded first. 

The half finished project, lets say you put one coat over half of it. When you go back you should use the same product and put a coat on the unfinished half. After that dries scuff sand all of it and put another coat on everything. It wouldn't hurt if you overlaped a little as long as it was thin. If you put it on thick where it overlaps you would see a difference in the thickness of the finish where it got two coats. If you put two coats on half the project then you need to put two coats on the other half so it's all even and then coat all of it.


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## mixer440 (Oct 24, 2009)

Thanks Steve.

I'm probably over analyzing this, but it seems like a dog chasing its tail. But, I got the idea about equal coats.

I just don't seem to get these bigger things finished quickly when all I can do is hand brush on....thus the overlaps at the edges (if there is an edge-Ha !)


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## DST (Jan 10, 2011)

Just wondering what the advantage to putting shellac over poly would be? Seems like a sealcoat would be best going on first


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## cabinetman (Jul 5, 2007)

mixer440 said:


> Can dewaxed shellac go on top of water based poly ?


What would be your reason to put shellac on top of either WB or oil base poly?


















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## ShellacFinishes (Jul 16, 2014)

Like others, I am wondering too about shellac over poly?? Although adhesion should not be a problem


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## Steve Neul (Sep 2, 2011)

One of the reasons a person might want to put sealcoat over polyurethane is a lot of finishes won't adhere to polyurethane but would adhere to sealcoat. It's easier to use a barrier coat than to strip the poly off.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> One of the reasons a person might want to put sealcoat over polyurethane is a lot of finishes won't adhere to polyurethane but would adhere to sealcoat. It's easier to use a barrier coat than to strip the poly off.


This is not the OP's answer, it's your answer. What finishes are you saying won't adhere to polyurethane?...and you didn't specify oil or WB. 

If you've got a film finish with either WB poly or oil base poly, there's no need to change to a different media. Lacquer is the only topcoat that would react. 


















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## Steve Neul (Sep 2, 2011)

cabinetman said:


> This is not the OP's answer, it's your answer. What finishes are you saying won't adhere to polyurethane?...and you didn't specify oil or WB.
> 
> If you've got a film finish with either WB poly or oil base poly, there's no need to change to a different media. Lacquer is the only topcoat that would react.
> 
> ...


It's not the OP's answer but the topic changed to why a person should need to use sealcoat over WB polyurethane. Polyurethane since it is harder finish with the polymer resins inherently has adhesion problems even putting another coat on of the same finish. Then for what ever reason the finish is changed either putting toners over it altering the color or changing to latex then sealcoat is a good barrier coat to start the transition. Even going to paint the shellac based bin primer doesn't adhere to polyurethane as well as if it were coated with sealcoat first.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> It's not the OP's answer but the topic changed to why a person should need to use sealcoat over WB polyurethane. Polyurethane since it is harder finish with the polymer resins inherently has adhesion problems even putting another coat on of the same finish. Then for what ever reason the finish is changed either putting toners over it altering the color or changing to latex then sealcoat is a good barrier coat to start the transition. Even going to paint the shellac based bin primer doesn't adhere to polyurethane as well as if it were coated with sealcoat first.


I would be interested in the OP's answer to the question.


















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## Steve Neul (Sep 2, 2011)

cabinetman said:


> I would be interested in the OP's answer to the question.
> 
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> 
> ...


Me too but it’s starting to look like he might not be coming back.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> Me too but it’s starting to look like he might not be coming back.


Why would he come back when you've taken over the thread?


















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## Steve Neul (Sep 2, 2011)

cabinetman said:


> Why would he come back when you've taken over the thread?
> 
> 
> 
> ...


You keep trying to blame me for your constant arguing. Use a little self control.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> You keep trying to blame me for your constant arguing. Use a little self control.


Another useless, pointless comment clogging up a thread. Just move on.:yes:


















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## Eddie Wallace (Jul 7, 2014)

cabinetman said:


> Another useless, pointless comment clogging up a thread. Just move on.:yes:
> 
> 
> 
> ...


If you wouldn't start your BS there wouldn't be any.


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## tpierce (Oct 14, 2013)

Eddie Wallace said:


> If you wouldn't start your BS there wouldn't be any.


Amen. Steve, sounds like you know your stuff. Not sure I could have answered it better! It's obvious you have done decorative finishing. Not just slopping on stain if you will.


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## Al B Thayer (Dec 10, 2011)

Neul is the finish guru. He's prolly finished everything from a table top to a banana peal. He drags me kicking and screaming because I hate new finishes these days.

Shellac is to wood what an aspirin is to people. Pretty much works on everything. It's over looked due to it not being the easiest material to use and so many are caught up in the poly for everything finish. I think shellac would stick to butter if you didn't brush too hard. Adhesion is one of its best qualities. And nobody does a french polish with poly.

Al


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## mixer440 (Oct 24, 2009)

Sorry about not getting back here soon enough, as it looks like I kicked over a hornet nest.

I do appreciate the comments and ideas.

Now the reason I asked the question was that I had to do some repairs to a piece I was working on.

Originally, I was using Western Oregon Maple and wanted to give it a bit more color, plus a seal coat----just a tad amber mind you. To do that I used some of the de-waxed Seal Coat shellac, let it dry and then proceeded to finish things with several coats of water based poly.

Fast forward a few months. I had to do the very minor repair which required shaving off some wood down way past the finish (1/16") in only a 2 inch area.

In that area the maple was now much lighter than the surrounding area. So, I figured if shellac would adhere to the surround poly, then I could overlap a bit with shellac to blend and then apply the poly once again to the repaired area.

I tried it in a test area and it appears to be working fine. The match is just dandy.

Hopefully it all makes sense.


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## cabinetman (Jul 5, 2007)

mixer440 said:


> Sorry about not getting back here soon enough, as it looks like I kicked over a hornet nest.
> 
> I do appreciate the comments and ideas.
> 
> ...


It does make sense. What you did was just to repeat (in a smaller format) what you did the first time.


















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