weirdest thing ever encountered when working with polyurethane

[ielongboardman]

this is honestly the weirdest thing i have ever encountered when working with polyurethane

the polyurethane i have is a fast drying superior durability clear gloss by minwax i applied a thin coat and set it out to dry. its been at least 3-4 days more than enough time for the polyurethane to dry. the odd part is that it is dry the touch completely but when i pushed my thumb into the finish it left a distinct finger print in the polurethane and after moving it around a bit with my finger (bad idea) the finish would peel off leaving a very sticky wood surface. generally i would suspect the weather but lately its been about 60-70 degrees as the low and thats at night well after i have already coated the boards and taken them inside. i have also though of the possibility of solvent contamination but this seems highly unlikely considering i used the same polyurethane on the exact same surface and one is now messed up and the other is completely fine

i honestly have no idea what is going on with this............

[sterlingc]

whats the surface like you applied it on? does the wood have some kind of funky chemical soaked into it or is it off-gassing and preventing the urethane from drying?

[NickAnzo]

lately its been about 60-70 degrees as the low and thats at night

I hate you

[ielongboardman]

I hate you

ha ha ha ya dude its pretty nice but the summers are brutal here

but the wood i am using is just regular hardwood and what do you mean by offgassing?

[mbease]

one thing that I could see causing this is applying the coats at random times and not waiting for the current coat to dry/cure correctly.

it is advised to wait at least 1 hour (average temp.) between layers to let the current coat to dry, or wait 24 hours before applying another layer as that is a good time during curing to apply more coats.

if this isn't the case you might have bought a bad can or something. Minwax polyurethane is very good stuff so there aren't any doubts about the brand.

[LaneMeyer]

where do you live that the winter lows are 60-70 degrees?

[samhell]

1. Are you using oil or water based Minwax?
2. Was there extreme humidity?
3. What did you sand the surface with before applying the poly?

[ielongboardman]

where do you live that the winter lows are 60-70 degrees?

hot and sunny phoenix,az

the polyurethane is oilbased and the surface was sanded with i think 180 grit and all the excess was wiped off with a t shirt

[Pleinair]

where do you live that the winter lows are 60-70 degrees?

It's about that temperature outside in California

[legendary]

Even though you say that you put it on thin, I have found this happen when Minwax is put on too thick. The outer layer dries, and it traps the inner poly and does not allow it to gas off and cure.

[Loki440]

sounds like your putting it on to thick, this also happens when you don't let a previous coat cure enough before the next coat.

[XphillipX]

Bruce Willis!

[nsc1120]

lemonade was a popular drink and it still it?

[ielongboardman]

Even though you say that you put it on thin, I have found this happen when Minwax is put on too thick. The outer layer dries, and it traps the inner poly and does not allow it to gas off and cure.

huh yeah i guess that would make sense since im using a high build polyurethane should probably change to polycrylic or maybe helmsman spar urethane?

[legendary]

Check the label on the can to see what the time period is that they suggest for adding coats. If you are using birch, here is what I would try. Seal the wood first with a sanding sealer. Let that dry. This will help keep the wood from soaking up so much poly. Sand lightly after it dries if needed. Apply your first coat of finish in a very thin coat and let dry for about 24 hours. Sand lightly, if you are using baltic birch you will need to as it usually raises the grain. Apply the second coat, you can go on thicker on this coat. Wait to dry for about 24 hours. Sand lightly with fine paper. Apply a third coat. Wait 24 hours. Sand lightly, Repeat coats and sanding till you get the finish thickness you are looking for. Allow extra material if you plan to wet sand / buff the finish.

[Geeezer]

... all the excess was wiped off with a t shirt

thats the price to pay for your climate in hot and sunny phoenix,az!

Wiping the board with a sweaty t shirt is your problem!

try a nice layer of epoxy. Dries pretty quick and is tough as old boots. I tried PU varnish and Yacht varnish but got similar results, I could scrape it off with my thumb nail. Epoxy needs a tactical thermonuclear device to shift it

[EnemaAZ]

I live in Mesa, and ive never had this problem, but its been really rainy lately, so i would not recommend trying to varnish. Pick a hot sunny day, and bring it in overnight. Ive had some major gluing trouble lately because of the rain.

[ielongboardman]

I live in Mesa, and ive never had this problem, but its been really rainy lately, so i would not recommend trying to varnish. Pick a hot sunny day, and bring it in overnight. Ive had some major gluing trouble lately because of the rain.

yeah dude this rain has been so random lately i think im gonna try helmsman spar urethane

[afi1014]

i have the same problem....and i want to know how to fix it?

[housecat]

Maybe did you paint the board and now the polyurethane is reacting to the paint? This is unlikely because you'd probably realize it first... As one of the above posters said, maybe the wood is chemically treated and now the polyurethane is reacting to it? Perhaps get some 400 grit sandpaper, gently sand off the current coat and try again