polyeurathane use after lacquer or shellac

larry merlau

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Delton, Michigan
ok have a possible project where the customer wants poly for finish.. i normally use shellac and or lacquer.. so what do i need to know before i fill my spray gun with this stuff? or should i just hand apply? they want a gloss finish.
 
Larry, Poly is going to dry much slower than lacquer leaving it open to collecting any airborne dust and such. Also, poly does not "build" like lacquer on additional coats. Yes, I would spray but very light coats.

Doug
 
If you're asking about spraying poly over shellac, I've done it - with disastrous results! Even though I'd scuff-sanded the shellac, the poly didn't bond to it, and just peeled away.

As for just using straight poly (no shellac under it), what Douglas said is correct. I'd also sand lightly between coats - and you'll likely only get one coat per day.

BTW, the waterborne polys are pretty good, too, but I still prefer the solvent stuff when I've gotta use poly.
 
unfortunately this client has specs poly, i didnt even attempt to talk to him on lacquer.. should have.. is there a argument for ploy over lacquer? in my eyes there isnt.
 
If you're asking about spraying poly over shellac, I've done it - with disastrous results!
...
BTW, the waterborne polys are pretty good, too, but I still prefer the solvent stuff when I've gotta use poly.

Really?

I put Flecto Varathane (which is a WB poly) over zinsser dewaxed shellac several times. Worked fine.
I've sprayed it only once -- I was not thrilled with how slowly it built up, but it worked. Usually I make smaller projects and then I brush it on. 3-4 coats and it's hard and glossy.
 
Larry fetch your self some Ben Moor's water base and shoot it on. You can shoot 2 or 3 light coats than let it stand over night hit it with some 220 and shoot a finish coat on. Last time I used a cheap gun from HD I'm off to see how it goes through my new spray fine but I'm thinking the CV tip in the spray fine is to big for the polly. I'll let ya know in a few hours.
 
Fibbed to ya on the brand. I'm shooting ZAR but the shop is just a bit to cold for fast drying so we are waiting for the second coat. Guessing about an hour.
 
Ok second and third done. Now it's wait and see if I need to knock it down tomorrow and shoot it one last time.
 
If you're asking about spraying poly over shellac, I've done it - with disastrous results! Even though I'd scuff-sanded the shellac, the poly didn't bond to it, and just peeled away.

As for just using straight poly (no shellac under it), what Douglas said is correct. I'd also sand lightly between coats - and you'll likely only get one coat per day.

BTW, the waterborne polys are pretty good, too, but I still prefer the solvent stuff when I've gotta use poly.

Jim,

The research I have done on shelac and poly reveals dewaxed shelac works fine under poly. In fact, Target Coatings sells a wb shelc that can be used under their poly. Did you use shelac that had not had the wax removed possibly?

I am getting ready to spray my daughter's blanket chest with dewaxed shelac as a sanding sealer and then Target EM9000 (I think) so this is an important subject to me.


Jack
 
If you're asking about spraying poly over shellac, I've done it - with disastrous results! Even though I'd scuff-sanded the shellac, the poly didn't bond to it, and just peeled away.

Really? I put Flecto Varathane (which is a WB poly) over zinsser dewaxed shellac several times. Worked fine.

I'm also confused. I use shellac between finishes when I want to be sure they will bond. This is a common use of shellac. I think something else may have been in play. A contaminant? Something present or carried over in the abrasive used?

We all have our tastes and I'm sure growing up in the California-poly-coated-red-oak jungle that plagued our local furniture offerings for a couple decades contributes to mine. I find the thick, plastic-y look of poly bothersome even when disguised behind a lower sheen. However, the customer is always right and their tastes should win all arguments entertained. Forge ahead, and good luck ;-)
 
Jim,

The research I have done on shelac and poly reveals dewaxed shelac works fine under poly. In fact, Target Coatings sells a wb shelc that can be used under their poly. Did you use shelac that had not had the wax removed possibly?
I am getting ready to spray my daughter's blanket chest with dewaxed shelac as a sanding sealer and then Target EM9000 (I think) so this is an important subject to me. Jack

I did use dewaxed shellac. SealCoat®, in fact. The Cabot (brand) poly just peeled away from it. There was no bonding at all.

Personally, I hate poly, with the possible exception of Arm-R-Seal - but I've never tried it over shellac. I use Seal-A-Cell under that.

My preferences now pretty much run to the waterborne lacquers - either Target or General Finishes 'Enduro.'
 
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