Too cold? Not enough stirring? Or something else?

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I'm brand new here. This forum was recommended by a friend. I'm an avid DI Y-er but finishes are not my specialty.
The problem: I built a steam radiator cover (out of red oak) for my 8mth old son's room (turned out great). The minwax oil based fast drying semigloss polyurethan e has not dried properly and is giving off a smell as the radiator heats up . I'm concerned about safety (fumes) so I have removed the cover until I c an fix the problem.
The finishing process: We live in a small 2 bed APT in NYC, so I have less than ideal circumstance s for woodworking.
For the first coat I applied the polyurethane directly to the (sanded/wiped clean) surface of the wood. *it it possible that the can was not stirred well enough. * the first coat was possibly thick but had no runs. I sat out side my apt in the sun waiting for the finish to off-gas. After an hour I brought it inside to cure.
After 4 hours the finish seemed cured (the can recommends 3-4hrs). I sande d with 220 and wiped clean with a slightly damp cloth.
For the second coat (around 9pm) I had to change location, so I applied the finish standing inside our apt with the project sitting outside on the fir e escape (on a cardboard box to catch drips). It was cold - about 50 degree s. I left it out there to off-gas for an hour, then brought it inside to cu te overnight. *Again the can was possibly not stirred well enough.
The next day everything seemed fine other than a slight oily film (like the project had the tiniest film of cooking oil over it). I figured it would h arden with heat and time, so I attached the aluminum mesh and installed it. .. And now we have the problem.
Thoughts, guys? I'd love to avoid sanding this whole thing back to bare wo od (as it will be by hand on my kitchen floor).
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snipped-for-privacy@gmail.com wrote in

In my experience poly smells for a while. It seems that whatever formula Minwax is using now is worse than it was 10 or so years ago, too.
In any event, my first thought would be to just leave it awhile - the smell will probably go away in a week or so.
My second thought is, you could try sealing it with shellac.
FWIW, shellac is a non-toxic finish (they coat M&Ms with it), so if you're making other kid-stuff that needs a finish you might consider it. Altho toys and things like that are generally best left bare wood.
John
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On Saturday, October 25, 2014 12:12:16 PM UTC-5, John McCoy wrote:

The formula was changed to accommodate the newer VOC concerns.

I agree with John. Just let it sit a good while.
*First coat applied on raw wood: Some has soaked in, a bit, so it would take longer to dry, than what the can says. Would have been good to let it dry overnight. Despite the short time before recoating, it should cure, properly, after a good week.
So, until then, the penalty assessed is: Your son sleeps with Mom and you sleep on the couch!
Sonny
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Thanks, John. I'll definitely look into shellac.
Update: the finish seems fine until I run fingers over it. There is a slight oily residue that comes off on my fingers. This hasn't gone away after a week. Is this normal for poly??
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On 10/25/2014 3:38 PM, snipped-for-privacy@gmail.com wrote:

It's a great finish, but it does not like heat. I would have waited 24 hours before recoating. Then I would wait a week before putting it to use.
Just wait and see what happens.
I'm not a big poly user, but I don't think you need to stir it.
--
Jeff

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On 10/25/2014 2:38 PM, snipped-for-privacy@gmail.com wrote:

Not normal. Is that "new" can of finish?
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On 10/26/2014 12:51 PM, Leon wrote:

I find myself especially curious about this so I'd like to recap.
Its seems we have several factors here, and two questions. The first question: what accounts for this strange result?
Here are (some of the) possibilities:
1. The state of the can of finish.
Do these have date codes? I have seen some pretty un-saleable things returned to the shelves of Home Depot. What happens to old poly?
2. Insufficient stirring.
The instructions say to mix thoroughly before - and even during - application. But what happens if we don't? Is it simply that we will have a more dilute mixture near the top of the can? If so it's hard to imagine that causing the reported symptom. After all, some of us have thinned poly on purpose without that result. Or maybe something else separates out as well?
3. The temperature.
If I remember correctly, poly "dries" by two processes. First the solvent evaporates, then the "polymerization" reaction occurs over time. If memory serves, the second reaction at least (the "curing") is retarded by lower temperatures. But the piece was eventually brought into a heated space. Would it then cure properly, even if the process had been slowed by the lower temperature?
4.The timing.
The online instructions say to wait 4-6 hours between coats. So again, what happens if we don't wait long enough, "long enough" perhaps being lengthened by the ambient temperature during the first hour outside? Does the second coat prevent enough oxygen from getting to the first coat, perhaps?
5. The radiator heat.
But of course, all of the above is to some degree an academic exercise, with the possible exception of the condition of the can of finish. What does Tim do now to fix it?
I'm guessing he finished the inside surfaces of the project as well. So perhaps the first bit of advice would be to try out a repair strategy on the inside surfaces. If successful, repeat on the surfaces that will show.
Finishing figures prominently among the topics I'm ignorant about, but if this were my own project I'd be inclined to try removing the oily residue with a solvent like mineral spirits. If that seemed successful, I'd probably scuff the finish a little and reapply poly - from a different can - just to be safe. I'd stir, and watch the temperature, and wait a whole day before considering any further coats.
One other thing:
Perhaps, given the apartment setting and his infant son, a water-borne poly would have been a good choice. I thought I read somewhere that despite being *carried* by water, the poly is still poly. Does this mean that he could try water-borne poly over what he's got (with some surface prep, but without sanding down to bare wood)? Or is there perhaps some other choice that's sufficiently non-hazardous to do entirely inside his heated apartment?
Sorry for the long-winded questions (my specialty), but I have taken a special interest in this young man's predicament for some reason. :)
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On Sat, 25 Oct 2014 08:35:19 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Your concern about not stirring the polyurethane well enough is unwarranted. The thicker contents at the bottom of the can that needs stirring will only effect the sheen. That contents is not present in the clear gloss polyurethane and that is why that polyurethane is glossy.
Don't be too concerned about the smell unless it really bothers you or your son. It will stop soon. When polyurethane is curing it gives off those fumes. The off-gassing is exacerbated when it is heated such as being near a radiator.
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It may be dry to the touch but it won't be cured for at least two weeks, month is closer.
I hope you dried it after wiping with before the damp cloth before applying coat #2. ____________

If it had an oily film, regardless of how slight, you didn't stir it enough. The 50 degree weather didn't help either. __________________

Try wiping it down well with paint thinner. If the oily film goes away, scuff sand and apply another coat after stirring well. "Well" = twice what you think it needs.
--

dadiOH
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On 10/25/2014 4:44 PM, dadiOH wrote:

I wondered about that possibility as well. Any one else have thoughts on this?
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Mike Marlow wrote:

"Ed Pawlowski" wrote:

One of the reasons I left Ohio was to get away from weather problems like this.
The only way to do it was down in the heated basement, apply a coat and allow a week to cure between coats and learning to live with the stink.
Based on what I read so far, it's time to go to Goodwill and buy a bag of rags, then to HD for a gallon of denatured alcohol.
Wipe as much of the defective material as possible, then sand out starting with 150 grit using the +/- 45 degree bias method.
When finished sanding, WAIT a WEEK before applying new material that has been prepared like Bond's martini.
(Don't bruise it.)<grin>
Wipe the surface down one final time before applying new finish.
And now the tough part, keep the piece INSIDE and learn to live with the stink while it dries.
After the 2nd or 3rd day, the stink won't be so bad.
DAMHIKT.
Lew
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On 10/25/2014 11:25 PM, Lew Hodgett wrote:

I'm not sure about acetone..
--
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wrote in message
I'm brand new here. This forum was recommended by a friend. I'm an avid DIY-er but finishes are not my specialty.
The problem: I built a steam radiator cover (out of red oak) for my 8mth old son's room (turned out great). The minwax oil based fast drying semigloss polyurethane has not dried properly and is giving off a smell as the radiator heats up. I'm concerned about safety (fumes) so I have removed the cover until I can fix the problem.
The finishing process: We live in a small 2 bed APT in NYC, so I have less than ideal circumstances for woodworking.
For the first coat I applied the polyurethane directly to the (sanded/wiped clean) surface of the wood. *it it possible that the can was not stirred well enough. * the first coat was possibly thick but had no runs. I sat outside my apt in the sun waiting for the finish to off-gas. After an hour I brought it inside to cure.
After 4 hours the finish seemed cured (the can recommends 3-4hrs). I sanded with 220 and wiped clean with a slightly damp cloth.
For the second coat (around 9pm) I had to change location, so I applied the finish standing inside our apt with the project sitting outside on the fire escape (on a cardboard box to catch drips). It was cold - about 50 degrees. I left it out there to off-gas for an hour, then brought it inside to cute overnight. *Again the can was possibly not stirred well enough.
The next day everything seemed fine other than a slight oily film (like the project had the tiniest film of cooking oil over it). I figured it would harden with heat and time, so I attached the aluminum mesh and installed it... And now we have the problem.
Thoughts, guys? I'd love to avoid sanding this whole thing back to bare wood (as it will be by hand on my kitchen floor). ********************************************************************************* Give it time. It is not unusual for it to out-gas for 4 days or more. Being around some heat will speed the process and make it harder. -------------------------------------------------------------------------------- Jim in NC
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Mike Marlow wrote:

"Ed Pawlowski" wrote:

Lew Hodgett wrote:

"woodchucker" wrote:

If it won't attack "weakened" poly, then it's acetone or xylene time.
Lew
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Considering he's worried about an infant in the house, acetone or xylene is probably the last thing he wants to experiment with.
John
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"John McCoy" wrote:

Lew Hodgett wrote:

"John McCoy" wrote:

That should probably apply to the total project if the infant can't be isolated when working on the project.
Basic problem of working inside during winter months.
Lew
Lew
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Like you, finishing isn't really my strong suit. But my understanding is that, if you recoat too soon, you're basically just creating one very thick coat. Since the solvent has to evaporate, and that happens very slowly once a skin forms on the finish, very thick coats are not recommended...
(I note that professional finishers often spray on coats on a much shorter schedule than 4-6 hours. But they're spraying, so a much thinner coat to start with).

Water-borne poly is just that, regular poly carried by water. To be specific, it's regular poly in an emulsion in water. Once the water evaporates, you're left with the normal poly solvents (just much less of them).
The only non-hazardous finish that comes to mind is shellac. But as someone pointed out (and I'd forgotten), that's not such a good choice with the heat from the radiator.
John
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On 10/27/2014 12:05 PM, John McCoy wrote:

Actually it can be worse than 1 thick coat. In some situations the gassing off will cause a problem for the new coat, rough finish, air bubbles, incomplete cure underneath...
It's not just a thicker coat.
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Jeff

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Personlly, going with daddiOH and Mike Marlow on this one.
Important note to all finishers:
READ, UNDERSTAND, AND FOLLOW ALL INSTRUCTIONS ON THE CAN. While many think they know the manufacturer's product better than the manufacturer, this si mply isn't true.
Poly will indeed desegregate with the heavier resins going to the bottom of the can and the ligher oils coming to the top. While it may not be appare nt to the naked eye, especially when looking down into a can, it happens. Storage in hot weather can really make a difference in how fast this happen s, too. (Hint: hotter weather makes the oil rise..)
No doubt, you have the long oils on top of your project. They may not dry for a long time, and if they do, your finish is already fouled. I can tell you as a professional that does this, you cannot "salvage" a finish. You either do it right or wrong, there is nothing in between. Don't spend the next couple of weeks trying to put a band aid on this project. If your pol y isn't dry to the touch in a day, unless there are unusual weather conditi ons, something went wrong. Strip the old stuff off, buy new poly, STIR IT UP, and apply it. Put this behind you and go to the next project.
Robert
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How old is old? I've used stuff that was at least five years old, maybe ten, without problems. _______________

If I don't use a can of oil paint for some time the linseed oil separates out and floats on the top. Stirring gets it mixed back in.
If the varnish is non-glossy, one also has to mix in the flatting agent...the gelatinous goo in the bottom. Takes lots of mixing. Time was that the flatting material was talc; now I suspect it is fumed silica. _________________

Can't say for sure but I don't see why not. Regardless, the finish should NOT have an oily film at any time under any conditions. _____________________

All the floors in my house are Saltillo tile top coated with oil poly. I apply 3-4 coats in one day, waiting between coats until I can walk on it without sticking. That is usually 3-4 hours.
I mop on the poly so coat thickness varies considerably. The tile is also a bit curved so in areas where the coat is particularly thick, it will run to and pool at the corners between tiles. I try to avoid that, I look for and smooth out any I see, but it is pretty much inevitable that I'll miss some. In the thickest spots, the poly winds up 1/16" thick - maybe more - but eventually dries and cures. _________________

ONLY mineral spirits or other similar (paint thinner, turpentine).

If you wait a day, you have to sand between coats. The "window of opportunity" for recoating without sanding stops at about eight hours IIRC.
I would also want to assess the condition of the varnish once/if the oily residue can be removed. _________________

Sort of. It is polycarbonate + acrylic. Oil poly is polycarbonate + (probably) alkyd, could be phenolic but not likely.
Water base stuff has two useful features: 1., it doesn't color the wood and 2., it washes out of applicators. When you get those you give up hardness, durability and longevity. ________________

Once cured, you can put water poly over oil poly and vice versa. __________________

I'm pleased to note that, I will rest easier tonight even though this isn't email.
PS: I use avast! too but I don't shill for them :)
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