Humidity while painting

[DanB]

Thanks Randy,
That sounds like a great tip holding a shop light while painting. I will try it for sure as there are always places I just don't get the reflection I need.

[DanB]

I tought I would follow through and post a couple pics of the first cross coat in yellow. Steve Kellender affectionately calls his paint "Please don't hit me yellow" (Piper yellow)...I think I will have to follow up and call mine Please Please don't hit me yellow ...or translated..."Are You Freakin Blind?"
yellow3.jpg
yellow4.jpg

[DanB]

Dan, it's starting to look like an airplane. A little each day.
And by the way it's "Don't Kill Me Yellow" but I don't think that's what Poly Fiber calls it.
Dan, it wasn't long ago your Kitfox looked like this. A little each day. It's going to turn out great. Nice work.
http://www.teamkitfox.com/Forums/alb...&pictureid=462

Thanks Steve,
Finally seeing a color on it certainly provides inspiration. Thanks for sharing the pic...I hadn't seen that one.

[Slyfox]

I'm new to the group so I say, HI! to everyone.

On painting, I did mine 3 years ago now, the polytone is easy to put on, but doesn't hold up to well, at least for me. I put an average of 250hrs a year on the fox and it shows. The bottom, yuk, and to get the exhaust off, a lot of work. My recomendation is to put the eurothane over the top. If you want to make the polytone shine, the trick is to put I think reducer in it(the stuff you put in for painting in high temps, so it dries slower) and than shoot in 65degree temps, than the drying time is real slow. THan it will shine a little.

My plan is to repaint my airplane after I replace the engine, I WANT THAT 912S, ya baby. But this time I'm going with the Stewart systems, I put it on my newest airplane, RV7A, which is almost ready, you know the 10%left with 90% of my time. This stuff is different to put on, but shines nice and cleanup is a breeze. Not to mention the risk factor is gone while spraying. AFter it dries the MEK won't take it off either.

I don't think the humidity is a problem as much as a cool 65 for spraying. THe slower it dries, the better it looks. Have fun.

[Skybolt]

Dan B said >>"I decided to try a trick that Alan Nephews told me about. He said before shooting the color coats, put the paint into the freezer...it doesn't freeze"

I have heared this story many times, about placing mixed paint in the refrigerator....not so much the freezer!
If it is a non catalized paint, you will only change the viscosity. Making the paint very thick during spraying. As the paint warms up, this will make the viscosity thinner. So there will be difficulty knowing what is going on with the application.
With 2 component, catalized paints. Placing the mixed paint in a refrigerator will retard the chemical curing reaction. So the pot life is a little longer but can not be measured.
Again, the viscosity is realy heavy at first application.
What can this do for you? provide orange peel. Very heavy application and paint runs when the viscosity changes during the paint warm up.
From my experience, if the paint is at spraying temperature and you add your additives for the temperature per manufacturers recomendation, you will probably have the best results. Unless the coatings company gave you false information.

Note: the new waterborne paints will freeze if you place them in the freezer.

As to humidity when spraying. Good rule is to use a thinner or reducer, whatever the paint is that you are about to spray for the temperature you are spraying in.
High humidity with single component paints (no hardener) you will probably need a retarder to add to the paint. This reduces the risk of blushing.
As solvent evaporates from the coating, this has a cooling effect on the object. This cooling attracts water vapor that is in the air into the paint and you will have slow drying and this blushing or milkiness. The faster the flash off of solvent the more of this problem.
High humidity with two component paints (hardener required) Again, use the reducer or activator for the spraying temperature. Do not under-reduce or place the paint in the refrigerator as this has a thickening effect and you will be more prone to solvent pops as the water vapor enters the coating.

The problem normally faced whan spraying in high humidity conditions is the paint taking too long to flash (this is because there is no room in the air for solvent evaporation, it is saturated with water) Do not be tempted to use a fast reducer as this normally has the bad effect of causing solvent pops. (remember the faster the evaporation the more cooling effect and then the more problem of moisture entering the film. much like the water that collects on a soda can when you take it out from the refrigerator on a humid day.)

If you do not have the best conditions to spray a two component paint, wait until the conditions are more favourable.

Eric.

[DanB]

Eric,
Thanks for the reply and comments. You are actually the second person that has told me cooling down the Poly Tone will do no good. Cooling down the product is more than just a "story" as it is recommended in the Poly Fiber manual (P.82). Granted, it says the refrigerator, but I thought I would try something someone had success with. I will be the first to point out that I am new to painting and I am learning quite a bit as I go along...So it's all good.

From what information I can gather, there is one major thing that will make the finish glossier...slowing down the dry time. Two things are said to affect the dry time...1. Temperature 2. Adding Blush Retarder. The logic of cooling down the paint seemed reasonable to me and I have been using 8500 reducer (which just has more blush retarder compared to the R 65-75).

The concern of increasing the viscosity of the Poly Fiber Product is nill. If there is a change, it is not noticeable and though I have been learning my gun, it has been spraying quite nicely. The only thing I found I needed to pay attention to using near freezing paint is to watch for condensation buildup on the paint cup. At one point I had a water drip onto my paint...not a fun experience.

As I have had fairly good success with my paint job to this point, I see no reason to fix what aint broken, however, I am a bit curious now. The question is...can I produce the same finish I am currently getting without freezing the paint? I guess I will have to try it and report back.
Over and Out

[Skybolt]

Hi Dan.
It looks like you are learning the painting process quite well
I kind of agree with you.. from what you said above, If every thing is going and looking good, then why change?
The thing is with paint, if there is a problem it will either be an imediate problem or something that shows up later. Immediate= blushing, orange peel, craters (fish eyes), paint runs, solvent pops, lifting, bad or no drying.
Later= crazing, peeling, low gloss, staining.
Most paint problems are self inflicted. Preparation was not adequate, paint was not mixed correctly, application and equipment was poor, application environment was not adequate and post application mainenance was not good.

As to the Poly Fiber manual (P.82). They suggest or recommend placing the mixed paint in the refrigerator. I don't have the manual handy, do they say why they suggest or recommend this?

With Polytone, an air drying (not a chemical reaction) paint. All benifit from good quality solvents that are used for thinning and slow drying. So' in theory a slower thinner or even a retarder will boost the gloss. Not only this but you should also notice an easier application (keeping a wet edge) better underspray and overspray melt in and a far smoother paint job...less dusty and less orange peel effect.
I personally do not see why refrigerating the paint can help with these things.

Anyone reading this; it is so important to follow the technical data sheets of the paint materials that you will use.
Before application, make sure the environment is satisfactory. For your health and or the sake of the paint.

Eric.

[n85ae]

I took so long painting various parts, that I painted in everything from hot
humid 80's, to cold down to about 50. I like painting in the cold weather
better. The only probelm is it take a lot longer for the Aerothane to cure.
It still cures fine, and after 6 years mine still looks like new.

Regards, Jeff

[Skybolt]

I have painted cars in your area and also down in Houston. Years ago I painted in the middle and far east. I understand the conditions. Summertime, probably the most comfortable time to spray paint is early morning and before the moisture build up at mid day and showers in the afternoon.
Polytone is much like laquer, that was used to refinish cars in the old days;
air drying and sensitive to heat and humidity during application.
Always important is to choose the thinner / reducer for the temperature your spraying in. That would mean you will be using a slow solvent.

Now with the high relative humidity, this will be somewhat of a balancing act. First the humidity will slow down the evaporation of the solvents =if the air is saturated (with water)then there is not much room for the solvents to go too freely. If you have good ventilation (air movement taking the solvents away) during spraying and flash off this will speed up the evaporation time (or drying)
If you are starting to get milkiness in the paint (blushing) this is when you need a slower solvent or retarder. Because if the paint surface is starting to flash (form a skin) Remember, that there is a cooling down of the coating and object during evaporation and if there is too much water in the air you will reach a dew point on the surfave and this is the blushing.
A retarder (apart from other uses) will allow the coating to evaporate slower and therefore the coating does not get as cold =more resistant to hitting the dew point.

Hope this helps. Eric.

[n85ae]

Personally, I'd just get out the paint gun on the worst possible day and
spray some test panel and see what happened. Worst case with polytone,
you end up spraying another crosscoat anyway. Even if you do get some
blush, no big deal to hit it again later.

Aerothane on the other hand is a big pain with the waiting, and sanding
between coats.

Regards,
Jeff