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Never dealt with this before but it’s really frustrating. Just built a dining table and 2 other small projects with the scraps. I stained with Varathane stain then applied Varathane water based poly. I did 2 coats a day apart. My son placed a package we received on it 3 days after applying the poly and it left these white marks we have not used the table hoping it’s just taking longer to cure. Yesterday, a week later I touch it again to see and barely grazed it with my nail and it did it again. Feels as if we waxed the top like a soft layer that’s not setting in. We went with a matte finish as well. We previously built a coffee table same finish same cold conditions we live in Cali and it’s totally fine and set.

I saw people using a white pad and buffing the finish but I’m scared to do anything to it. Any advice is welcomed dying to use it.

  • Hi, welcome to SE. Could you edit the Question to include the name of the waterbased poly you used please? Not just the brand but the exact product name. And can you add some details about how you finished (no. of coats, gap between each one, how you applied it). – Graphus Feb 4 at 4:37
  • And to clarify, it sounds like you applied the finish ~ a week ago and have been using the table since just after it was dry to the touch, is that correct? If that is the case any product weakness aside (all finish types vary and there are good and bad ones) that's at least part of it as finishes take time to cure — to complete the process(es) by which they harden. Even with waterbased stuff that dries so quickly full cure can take a week or more at room temperature. Since it's winter, if you finished in a cold room that can have a marked retarding effect on hardening. – Graphus Feb 4 at 4:47
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Most water based polyurethanes shouldn't be that soft. Some points to consider in your case:

  • Time between coats of water based poly is typically 4 hours. Most manufacturers recommend sanding the previous coat if the time between coats is 24 hours or more. If you applied the second coat after 24 hours (a day apart, as you said), and didn't sand the previous coat, it might be that the new coat didn't adhere well.
  • Was the stain water or oil based? If oil, did you let it cure fully before applying the water poly? Not letting the oil based stain fully cure (a few days at least, preferably a week) will also interfere with the poly adhering.
  • 2 coats of poly are typically too little, especially with water based poly (which is thinner than oil based poly and easier to apply thinner coats (which is actually a good thing)). With the faster dry time it is pretty easy to apply 4-5 coats at the same time you could apply only 2 coats of oil based poly.
  • Finally, as mentioned by Graphus in the comment, there is a big difference between dry time and full strength cure time. This applies both to oil and water based polys. Most water based polys are dry after 4 hours, but are fully cured after a week or more. Some manufacturers list strength/cure time tables, for example 50% strength in 1 day, 95% strength in 7 days, etc. That should give you a good idea how long to wait before putting the item to use.

As an aside, I like using water based poly for floors (incidentally, also from Varathane) on my projects, inspired by Matthias Wandel from woodgears.ca, and apply 5-6 coats (over a day and a half) and waiting a week before putting the project to service. Testing on scraps, there is a very noticeable increase in strength over the week of curing.

Edit:

As to what to do now, your're best off with removing the existing poly (which is not adhered well to the wood). You can do this via sanding, scraping or chemical stripping. All of these will probably also affect the stain on the wood as well.

Once the existing poly is removed, reapply it carefully, taking into account the above points.

  • Thanks Eli. The stain is oil based. It says dries in an hour so I did it in the morning and in the afternoon I applied the poly. Is this why that happened? How can I fix it? – Daisy Feb 4 at 15:20
  • Yes, that would most likely cause a water poly not to adhere well. The stain should have instructions for top coating, have a closer look at the can. For handling the existing project, I'll update in the answer – Eli Iser Feb 4 at 17:11
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    Not letting the stain fully cure might cause this or contribute to it, but it is important to note that oil based stain can be used underneath water-based poly. – Charlie Kilian Feb 4 at 17:43
  • Sounds like that’s the problem. You guys have any suggestions on how to fix it? – Daisy Feb 4 at 23:01

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