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Discussion Starter · #1 ·
I'm having really severe problems getting my wipe on poly to set smooth. I've done one box about 5 times now, sanding the old off and re coating.
I have had good success with this before so am wondering whats changed.
Do any of you know if poly varnish is affected by the temps when its applied?
We are now into full summer, daily temps of 37c (98f) in the shade, and probably mid 40's (110f)in the garage on the shelf where the tin is.
I cant find any temp range on the tin, but do you think this could be the problem?
 

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The temp may be your problem Bob. Many finishes like poly are designed to be self leveling but if it's too hot it will dry before that can happen. You might be better off using rattle can finish until it cools off some.
 

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Agree with Charles. I use wipe on poly but try to stay away from high temperatures and high humidity.
 

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I went outside and sprayed a poly clear coat from a rattle can and it frosted up. It kinda looked milky or maybe I should say cloudy. I know this isn't your problem but I think my problem was humidity because I went inside where it is air conditioned and it was okay.
 

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if poly works like lacquer, the cloudiness you are describing is called "blush", and yes...humidity is the cause. With lacquer, you can sometimes avoid this with lacquer retarder to slow down the drying so the water has a chance to evaporate before it gets trapped. Again, I don't know if this is the same with poly.


Gary
 

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Discussion Starter · #6 ·
Looks like I'm screwed.
Humidity is almost 80% today, so that lets out the spray can.

My one chance is to clean it all off and reapply it in our bedroom as thats the only room we have air con on during the day because we just live outside in the shade for the summer.

And to make it worse I'm on a deadline with this one.
 

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Great question. I'm going to be doing some of this, and the humidity problem is good to know about in advance. Looks like the bedroom is the only option since you're on a deadline.
 

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Discussion Starter · #8 ·
I'm now in a dilemma.
I've sprayed a piece of scrap from this box with acrilyc laquer. Its taken fine with no bloom.

But if I want to spray the box I have to remove absolutely all of the oil based poly. Thats a lot of work, and I might find I've missed a bit and the acrilyc ballooons it.

Decisions decisions.
 

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Try a test piece with wipe on poly in the AC bedroom. AC tends to reduce himidity. I do wipe on poly with folded paper towels instead of a brush, which technique I found on an instructional site by someone noted for his finishing work. Can't find that video but it sure does the trick.
 

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Try a test piece with wipe on poly in the AC bedroom. AC tends to reduce himidity. I do wipe on poly with folded paper towels instead of a brush, which technique I found on an instructional site by someone noted for his finishing work. Can't find that video but it sure does the trick.
Tom, I believe that the AC tends to reduce the apparent humidity. If the air is cooler, it won't hold as much moisture. Think steam here.

At below zero temps, like -40º for example, the air won't hold any moisture.

The additional high heat that Bob is experiencing will also make the finish skin over very, very quickly. That will only compound the problem.

Perhaps trying to cool the lowest room in the house will help? Try doing the finish as close to the floor as possible.
 

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Discussion Starter · #11 ·
Hah, picture me laying on the floor wiping the box over....(dont have a basement).

Tom, I have been using old T shirts for wiping the poly since I started doing it, and all through the winter and spring have been happy. Now,. the thing just shows runs and blobs even if I wipe hard. In fact I'm wiping so hard that I'm now getting bare spots.

Keith, the air con removes vast amounts of water from the room. I shall have to put a humidity meter in there to check numbers. Outside is 65%, inside is almost 80% at ambient temps.

I dont trust myself to get all the oil poly off so spraying acrylic is not gonna happen on this box. I shall move the poly to the room tomorrow so it cools down before mixing it and try tomorrow evening..
 

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Discussion Starter · #13 ·
I cant believe how many times he wipes the already applied poly.
At the moment, before i got across that table length mine will be sticking to the cloth on the second pass, and dry on the third.

i need a double pronged attack here.
i shall go out and buy a new tin of poly today, and wipe the box in the air con room tonight.
What percentages are you using? At the moment its 85% poly to 15% white spirit.
 

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I cant believe how many times he wipes the already applied poly.
At the moment, before i got across that table length mine will be sticking to the cloth on the second pass, and dry on the third.

i need a double pronged attack here.
i shall go out and buy a new tin of poly today, and wipe the box in the air con room tonight.
What percentages are you using? At the moment its 85% poly to 15% white spirit.
I too was surprised at how long he continued to work that surface.

I've gone through dozens of gallons of Varathane over the years, but never used a paper towel to do the application. Always used a good quality brush. Get the product on the wood, then leave it alone.

I have an excellent book on varnishing, not quite the same as using poly, and the author swears by using disposable foam brushes. So it's definitely not a "one size fits all" deal.
 

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I have had trouble with oil based paint in Texas not leveling very well in the heat. I use a product called Penetrol in my paint and it helps. It takes longer to dry but the brush strokes disappear. Heat causes the oil paint try dry before it can self level. Forget water based paints in the heat the brushed strokes look bad to me. I don't know anything about poly finishes.

I wipe on tung oil a lot in Texas on furniture. I don't see the problems you are describing. Most tung oil does not have UV protection. I recently bought some UV protected Tung oil from Walmart. It was for teak patio furniture. I used it on my handles for the BBQ smoker. It seems to be working well. Time will tell. The spar varnish which I have used only lasts 3 or 4 years before it needs to be done again. I don't wipe it as I use a badger hair brush.
 

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Discussion Starter · #16 ·
I couldnt get any new poly today.
I have put the tin of poly and the white spirits in the fridge. the box is in the bedroom cooling down slowly. i'm hoping to get everything around 25c (77f) for mixing and applying.
I'll mix it and wipe tonight and see what the difference is. The air con has reduced the room humidity by almost 20% compared to the rest of the house, its down to 60% now, should drop a little more when I put the a/c on about 8pm.

If this doesnt work I shall have to strip it completely and spray acrylic.
 

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About maybe 20 years, maybe more, ago they starting coming out with fast dry finishes. Before that a coat of finish would take 24 hrs to dry instead of one or two hours. I started having problems at times when that happened. It became difficult to get rid of bush marks with some of the fast dry stuff in the right conditions. That's when the foam brushes started becoming an advantage to use.

A can of finish that is a year old or more can also cause problems. Some of the chemicals dry out and the finish doesn't work the same as new will. So a couple of suggestions I would say are to avoid anything that says fast dry if possible and buy tins that you will use up in a few months. Also try decanting as much as you will be using and put the lid back on the original container as soon as you do to keep the chemicals in.
 

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Discussion Starter · #18 ·
Charles, theres no dates on the tins that I can see, could have been on the shelf for 10 years and i wouldnt know. None of the ones I've used so far are quick dry.
I only take very small amounts at a time, literally measure teaspoons into a plastic cup (6 poly to one spirit). Up till now that has allowed me to coat on 2 consecutive days. Not any more.

This is the first summer I have tried to use this. I shall have to make other arrangements next year.
 

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I buy small cans of anything volatile and keep the caps very tight. I also cut a recess in a chunk of 2x4 and drop in small, 2 oz plastic cups to hold the poly in tiny batches. These are the same cups you find for relishes and dips in restaurants. Easy cleanup too and I'm not tempted to pour the remnants back into the can. Of course, out here in the desert, we just don't have moisture problems and the shop is air conditioned.

To me, the advantage of using paper towels is that you are putting on an ample coat, so it levels nicely. Over brushing a thin coat would help dry it out before it self leveled.
 

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Discussion Starter · #20 ·
Well, just coated the box. What a difference!

outside it was 33c (91f) and 65% humidity.
Cooled the room to 27c (80f) and the humidity went all the way down to 48%.

Mixed the poly and spirits while sitting on the floor (the things I do in the name of science).
6 tea spoons poly, 1 teaspoon spirits, stir thoroughly, my normal mix.
Wiped it with a folded paper towel as normal.

The difference was amazing, it wiped smooth. I coated the whole box without the slightest sign of stickiness.

Then I hit a problem. It stinks! No way was my missus going to let that stay in the bedroom all night so I had to drag it to another un cooled room.

Hopefully, the increased heat will make it set a bit quicker.
tomorrow is another day.
 
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