Glueing over shellac?

I prefinished parts for a project with shellac that I dyed. I taped off the glue surfaces so they would be bare wood to glue. But I missed taping one surface so it got shellaced. I did sand off the finish so it’s down to bare wood, which really wasn’t very difficult. But it got me thinking that it would just be a whole lot easier if there was a glue that would burn thru a finish and do a good job. Has anyone heard of such a glue finish combo? Maybe some sort of alcohol based glue that would burn thru shellac?

How is finish on the glue area any different than glue on the finish area?
I understand what you're after but where does it end. The danger of getting a burn through glue on pre-finished parts is the same as getting finish on wood meant to be bare.
IMO, Prep takes a lot of time and care but it usually rewards you in the end.

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Originally Posted by Edward Weber

............different than glue on the finish area?

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I learned early on that finishing before glue/assembly would make my life much easier, unless/until I progressed into spraying.

I use dye and gel stain to get to my end finish on QSWO pieces. White [and red] oak is open pore - very open. Any glue that gets into those pores blocks dye absorption, and stands out like a neon sign.

yeah, a glue that would burn thru a finish would be a disaster with squeeze out. But I still wonder if there is such a glue/finish combo.

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Originally Posted by Edward Weber

How is finish on the glue area any different than glue on the finish area?
I understand what you're after but where does it end. The danger of getting a burn through glue on pre-finished parts is the same as getting finish on wood meant to be bare.
IMO, Prep takes a lot of time and care but it usually rewards you in the end.

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You could try using a non-PVA glue such as polyurethane ("Gorilla Glue" or similar under a different name) for a mechanical bond, but for PVA, you need to abrade back to the bare wood for best results.

When masking for pre-finishing, there's a rough corollary to the "measure twice, cut once" thing..."check tape at least twice, before putting on the finish". :) :D

About 10 years ago i tried to dye PVA glue with transtint dye. That was a disaster.

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Originally Posted by Leigh Betsch

I prefinished parts for a project with shellac that I dyed. I taped off the glue surfaces so they would be bare wood to glue. But I missed taping one surface so it got shellaced. I did sand off the finish so it’s down to bare wood, which really wasn’t very difficult. But it got me thinking that it would just be a whole lot easier if there was a glue that would burn thru a finish and do a good job. Has anyone heard of such a glue finish combo? Maybe some sort of alcohol based glue that would burn thru shellac?

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I think it would be hard to get a glue that would burn through enough of the shellac to meet bare wood before drying. Plus, what would keep it in place while this happens, so it doesn't spread, if it's eating the finish?

As for type of glue, you could maybe try an alcohol-based glue. They make a few out there. One is Stauf WFR-930 Solva-Matic which is used for hardwood flooring. I don't know how it would react with shellac, but I assume since it has an alcohol carrier, it would eat the shellac pretty well.

Or, you could just use shellac as a glue. It actually works okay. Not as good as PVA, but it's not too bad. It's fine for certain applications that won't be under high stress or exposed to too much heat, moisture, or other chemicals.

And you could potentially make your own glue. Glue is just some kind of solid mixed with some kind of solvent that liquifies the solid and then dries out to allow the old solid to resolidify. For example, you can make super glue out of acrylic and acetone. Or you can make casein glue by combining milk curds with ammonia. Rubber cement is just latex and acetone or toluene. Just find something that dissolves in alcohol and rehardens.

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Originally Posted by Leigh Betsch

About 10 years ago i tried to dye PVA glue with transtint dye. That was a disaster.

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Not surprising...there may be something chemically amiss between the PVA and the dye. (My new entry in the list of "my favorite things" is the Titebond Dark PVA from their factory)

Good timing on the thread, I did a similar oops making a potato/onion/garlic bin. I prefinished much of it and forgot about attaching the base trim. I've been researching and saw some suggestions for Weld Bond. Any thoughts on if this will work? Seems it may be a good alternative to ensure you (and I) get a good bond.

I never found a glue to use.
I just sanded the shellac off and used titebond glue.

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Originally Posted by Robert Hartmann

Good timing on the thread, I did a similar oops making a potato/onion/garlic bin. I prefinished much of it and forgot about attaching the base trim. I've been researching and saw some suggestions for Weld Bond. Any thoughts on if this will work? Seems it may be a good alternative to ensure you (and I) get a good bond.

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