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Note, this is not for exterior use.

We bought an old Buffet and converted it into a vanity for our bathroom remodel. At the time we thought it was a good idea to seal it with a waterproof sealer and selected a deck sealer at Home Depot to accomplish that task.

We have yet to get to the point where we are installing the vanity in the bathroom, but while it has been sitting in the garage, I have noted that the surface is slightly tacky.

I also observed that a separate dresser that we rehabilitated and coated with polyurethane has a smooth glossy finish that is not tacky at all and seems to be waterproof(?). So we would like that on that vanity.

So my question is, Can we put a coat of polyurethane on top of the deck-sealer-treated Vanity? I.e. Will the polyurethane adhere to the vanity? Should we lightly sand it before application? Or is there another way to get the nice smooth glossy non-tacky finish?

As an aside, why would the deck sealer treated vanity be tacky in the first place?

UPDATE: OK, here is the stain and the waterproofing sealer that was used. My wife doesn't remember how many coats she applied. She actually disagrees with me calling it "slightly tacky" and says I should describe it as "if something sets on it awhile, it can very slightly stick to the surface". She says that's not "tacky".

sealer stain

hepcat72
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  • If it's still in the garage and you're some place that's very humid or especially cool it may have not been ideal conditions to dry/cure fully yet. What are the environmental conditions and how long has it been since the vanity was refinished? The deck sealer might have not been fully mixed or applied incorrectly. How many coats did you apply and what was the time between coats (if more than one)? What was the deck sealer? What existing finish was on the vanity before you refinished it? – gnicko Oct 27 '21 at 13:52
  • All great questions which I expected to encounter. My wife did the refinishing (and I altered the drawers and cut the sink hole), so I will have to consult her for the details, but what I do know is it was done in the summertime over a year ago, before we started the remodel project. I helped her sand beforehand. There was a stain involved, but I'll have to ask if it was in the sealer or separate. – hepcat72 Oct 27 '21 at 13:58
  • Hi, welcome to Woodworking. This sort of query is usually is, but this one most definitely is in the in depends category. One problem is that "deck sealer" is merely a description of intended use, not a product description per se. If you look at everything available sold to 'seal' you'll see a few different formulations to say the least! Now that aside the elephant in the room is that the surface is currently tacky, and as a general thing you never put finish onto a tacky surface. Let's say the two products are type compatible, you need to sort that out first before you proceed. – Graphus Oct 27 '21 at 14:15
  • "I also observed that a separate dresser that we rehabilitated and coated with polyurethane has a smooth glossy finish that is not tacky at all and seems to be waterproof(?)." Yup, that's basically what poly is for. All varnish dries hard, but polyurethane in particular cures to a hard, waterproof-ish (depends on no. of coats) and scratch-resistant film. "As an aside, why would the deck sealer treated vanity be tacky in the first place?" As noted these products vary a lot but many are made not to dry hard, plus it may be formulated so that LOTS of air/sunlight is needed to fully dry. – Graphus Oct 27 '21 at 14:27
  • This should have been moved from [diy.se] instead of cross-posted. That's generally frowned upon. – FreeMan Oct 27 '21 at 16:33
  • Sorry. I'll delete the other (if I can). – hepcat72 Oct 27 '21 at 19:29
  • Can you update with exact name of products please? Or image of both containers – Volfram K Oct 28 '21 at 05:22
  • Yes I will. I asked my wife last night and she can't remember the brand let alone the specific product. She has to find the can. Apparently, it was longer ago than I realized. She said we did it in 2019. Time flies. – hepcat72 Oct 28 '21 at 12:05
  • Ok. I have added images of the products used and some clarifications recommended by my wife. – hepcat72 Oct 28 '21 at 15:16
  • "if something sets on it awhile, it can very slightly stick to the surface" I'm agreeing with your wife on this one. I'd imagine that just about any furniture sitting in a hot, humid garage will allow things to slightly stick to them if the thing has been sitting on it for "a while". – FreeMan Oct 28 '21 at 15:21
  • Alright. I concede. I guess I just didn't know the precise definition of the word "tacky". So if that's the case, I'm guessing there's nothing out of the ordinary to "solve" before endeavoring to apply poly? Do you know if poly will adhere given the sealer used? And should I lightly sand or treat with a stripping agent or something before applying polyurethane? – hepcat72 Oct 28 '21 at 15:25
  • I'm with you here. You said "slightly tacky" and the behaviour you describe could fall under that (admittedly imprecise) descriptive phrase. – Graphus Oct 28 '21 at 18:25

1 Answers1

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Can you apply polyurethane on top of wood that has been treated with a deck sealer?

In this case, yes.

As noted in the Comments "deck sealer" is a catch-all descriptor for a range of dissimilar products that are just sold to do (roughly) the same job, but not in the same way. Some are penetrating oil finishes akin to "Danish oil"1; some are waxy penetrating finishes; some are film finishes, including the Behr one you used.

Behr's product page for Transparent Waterproofing Wood Finish describes it as a 100% acrylic formulation, so there are no waxes or non-drying oils to worry about that would interfere with bonding of either waterbased or oil-based polyurethane.

You ask in a Comment whether you should lightly sand and the answer is basically yes. See recent Q&A which covers overcoating existing finishes; in short you want the surface clean and matt.

I would be inclined to strip this and begin from scratch, but you don't have to. Stripping is a tedious, messy job that you'll hate doing but I think ultimately it will give you a better result, both visually and endurance-wise.

The good news is you can easily preview your results without incurring any penalty — test the poly on a small area of an inconspicuous or less-critical surface of the vanity, prepped as you will prep the rest of it (i.e. cleaned and lightly scuffed up), and see how it goes.

If it looks good and the poly dries nicely you should be good to go. If unfortunately it doesn't you should strip back and begin again, if you want to use poly.

Another option
Given the deck sealer is made to be so waterproof and the slightly tacky surface is the only real issue you have with it you could just wax it.

Wax increases sheen, improves beading, and it should solve the slight pressure-sensitive tackiness.

I'd recommend using a commercial paste wax here, such as the venerable Johnson Paste Wax, and not a wax-based liquid polish2.

1 So a heavily thinned mixture of oil and varnish with lots of driers added to ensure fast drying.

2 Because the latter may contain oils as well as waxes (making them an inferior product), but may also be formulated with solvents that could attack the acrylic deck sealer.

Graphus
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  • I've been thinking about this question and I like Grapus' answer. Especially the last recommendation: Try some paste wax. You could probably get away with only waxing the top surface for now, and if it works, you can do the rest. It should only take 15-20 minutes, and can be removed (pretty much) if necessary. And... he used the word "venerable" describing paste wax! – gnicko Oct 28 '21 at 23:35
  • @GregNickoloff, minor correction: I used venerable to describe Johnson's paste wax since it has seemingly been around forever :-) Oh and BTW, no upvote? I don't need the points of course but curious about why. Only the other day one of my answers got two corrections from other members and neither of those people gave it an upvote, so, achem, clearly they thought it wasn't useful.... although it was important to correct minor grammar points ;-) – Graphus Oct 29 '21 at 07:12
  • Lack of an upvote was an oversight...which has been corrected. I've been using the SE phone app lately and find it kind of hard to manipulate. Forgive me, I'm old. – gnicko Oct 29 '21 at 11:51