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Polly over shellac

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Forum topic by lumbering_on posted 11-12-2018 01:31 AM 751 views 0 times favorited 15 replies Add to Favorites Watch
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lumbering_on

578 posts in 909 days


11-12-2018 01:31 AM

Topic tags/keywords: question finishing

I’ve heard many times that I shouldn’t put polly over shellac, but I’m helping a buddy of mine refinish his coffee table and he’s had a bad time with rings from people not using coasters. Normally, I would just use polly, but he insists that he likes the look of shellac.

Anyone have any trouble with putting polly over shellac, or is it something you can do?


15 replies so far

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bandit571

23176 posts in 3102 days


#1 posted 11-12-2018 03:41 AM

Get the De-waxed Shellac….and then Poly will stick to it….it is the waxed shellac you would have trouble with. Been using an Amber “sealcoat” from Bullseye. No problems.

-- A Planer? I'M the planer, this is what I use

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lumbering_on

578 posts in 909 days


#2 posted 11-12-2018 04:18 AM

Bandit, thanks for the info. Just a quick question, as I’m not a shellac expert. The normal Bullseye is a 3lbs cut, but Sealcoat is only 2 lbs, would that just need an extra coat, or is there an extra step involved? Thanks.

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bandit571

23176 posts in 3102 days


#3 posted 11-12-2018 04:53 AM

Used to be, I “cut” the 2lbs down to 1 lb, with De Natured Alcohol….lately, I just brush it on, right from the can. I usually go with 2 coats Shellac, then a coat or two of Poly, depending on how the first coat looks.

Coat of weathered oak stain, 2 coats of amber shellac, one coat of poly clear gloss…

Wood is Ash.

-- A Planer? I'M the planer, this is what I use

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TheFridge

10858 posts in 1905 days


#4 posted 11-12-2018 06:01 AM

Haven’t had a problem.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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Hermit

231 posts in 1744 days


#5 posted 11-12-2018 09:34 AM

Here’s a video that might help you out from the wood whisperer

https://youtu.be/7kCnmW6mKCM

-- I'm like the farmer's duck. If it don't rain, I'll walk.

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lumbering_on

578 posts in 909 days


#6 posted 11-12-2018 02:44 PM

Bandit, nice work. Good to know this should work.
Hermit, thanks for the link.

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MJCD

591 posts in 2790 days


#7 posted 11-12-2018 02:49 PM

I often use SealCoat under poly. It is critical to allow the SealCoat to fully cure.
MJCD

View Fred Hargis's profile

Fred Hargis

5585 posts in 2912 days


#8 posted 11-12-2018 05:44 PM

I think you’ll have a problem outside of varnish/shellac. If that table has ever been waxed with some of the aerosol stuff used by many homeowners you might find a problem called “fisheye”. I suggest you give it a thorough cleaning first (TSP works well) then coat it with the shellac. If the cleaning misses any, the shellac will seal it in. If you are 100% posilutely sure it’s never been contaminated with silicone, then your good to go (following the above).

-- Our village hasn't lost it's idiot, he was elected to congress.

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a1Jim

117655 posts in 3996 days


#9 posted 11-12-2018 05:51 PM

Shellac is compatible with all finishes with perhaps the exception of Milk Paint ,this is why you can use it in between types of finishes that are not compatible with each other.

https://www.artisticwoodstudio.com/videos

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lumbering_on

578 posts in 909 days


#10 posted 11-12-2018 06:34 PM


I think you ll have a problem outside of varnish/shellac. If that table has ever been waxed with some of the aerosol stuff used by many homeowners you might find a problem called “fisheye”. I suggest you give it a thorough cleaning first (TSP works well) then coat it with the shellac. If the cleaning misses any, the shellac will seal it in. If you are 100% posilutely sure it s never been contaminated with silicone, then your good to go (following the above).

- Fred Hargis

I’m not sure what he’s used, so my plan was to use paint stripper, then sand it down. It’s not a veneer, so I don’t anticipate any issues. Do you think I should use TSP in these steps? I generally only use it when I’m repainting as it saponifies the grease, but I not exactly sure how that would work with silicone based wax.

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Fred Hargis

5585 posts in 2912 days


#11 posted 11-12-2018 07:37 PM

If you use the stripper, and then sand it down I would think you would have done as much as possible to mitigate any contamination and you probably wouldn’t need the TSP. I would probably still use the seal coat just to be safe. Silicone can be really hard to remove depending on how much there is.

-- Our village hasn't lost it's idiot, he was elected to congress.

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Holbs

2213 posts in 2448 days


#12 posted 11-12-2018 09:21 PM

to my understanding…using the regular BullsEye Shellac with wax under Poly creates a problem because the wax ingredient micro cracks as time goes by. I found this out AFTER my plantation shutters. So far so good a year after but I fully expect issues in the next couple years.
Or maybe it’s not micro cracks but the wax changes of hue color a slight degree to be noticeable under the Poly. I forget :)

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

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OSU55

2357 posts in 2408 days


#13 posted 11-15-2018 09:12 PM

Not sure about micro cracks, I think its just the wax thats in the shellac which affects adhesion. No issue using dewaxed shellac under poly or a wb finish. For a refinish the shellac can help seal previous sins, but not sure it helps anything under ob poly on unfinished wood. Do you know what the previous finish was that allowed water rings? Never had a problem with them with a properly applied ob poly finish.

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WoodenDreams

620 posts in 330 days


#14 posted 11-16-2018 05:15 AM

For client I took a old rocking apart , and replaced all the connecting joints, then put poly over the shellac when I was done. They were ok with putting poly over the shellac cause they didn’t want to spend the extra money for me to remove the shellac. The Poly is holding up.

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Fred Hargis

5585 posts in 2912 days


#15 posted 11-16-2018 11:37 AM

It’s what OSU55 said, the adhesion problem is why it’s often suggested to not use shellac under urethane finishes. But the problem isn’t actually the wax; it’s the urethane resins, which tend to inhibit adhesion. So using dewaxed shellac solves the problem, or using any finish that doesn’t have urethane resins. If you use an alkyd resin varnish (P&L 38, or SW Fast Dry Oil Varnish) it doesn’t matter what shellac, if any, you put under it. It should be said, there isn’t a guarantee you will have problems if you put urethane finishes on top of waxy shellac….just that you might have problems. But the risk isn’t worth it to me, so it’s the old ounce of prevention beats a pound of cure thing.

-- Our village hasn't lost it's idiot, he was elected to congress.

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