White haze or fogging on paint

I've been having some frustrating problems with my paint lately.

I'm shooting it out of a Iwata airbrush, and I'm thinning it about 300%

I've decanted some fresh Tamiya out of a can and added its appropriate thinner, I let it sit anywhere between 20 minutes to an hour

when I shoot it, it leaves a white film or a foggy look to some areas.

This has been happening quite a bit lately and I'm wondering if anyone can help me figure out what's happening here.

I'm priming with Duplicolor and Tamiya primers and I don't have problems with Urethanes

I normally don't have a problem with Tamiya over these products either, but something is happening and I don't know what :banghead:

Do you have a picture of what is happening? I see you are in Indiana, what is the humidity like there right now? that can affect the way the paint acts. Also, what color are you spraying? If it is a solid color, see if you can get the same issue to occur on a scrap body, or scrap plastic. If so, try putting some clear cote over it. I've had this issue with some dupli color spray cans. The effect should have nothing to do with your equipment. It has to do with the chemical reactions or the conditions you are spraying in. Also, be specific, which thinner/reducer are you using? Give us as many details as possible

You're thinning decanted TS 300%? Wow, that seems very high, but I'm sure you know what you're doing. I find that 50-50 is more than enough to make it air brush well, but I don't have any humidity problems so what do I know? ;)

That's a humidity problem. I'm in western Illinois and haven't been able to paint for six or more weeks because of the humidity. It just won't go away.

There isn't a whole lot you can do about it unless you are flexible about where you can paint. A food dehydrator can help if you can shoot paint and then quickly get the body into the dehydrator. Also, sometimes you can paint and then quickly run the body into the house (assuming that it is air conditioned and, hence, less humid).

I do hope you have other projects already painted that you can work on until the humidity abates. Good luck!

As others have said the cloudy "blush" your getting is due to water vapor condensing from the air on the surface of your fresh paint. Realize that when you lay down a fresh coat of paint the solvent immediately begins to evaporate. Evaporation requires a tremendous amount of energy which is extracted from the surrounding air in the form of heat. This, in effect chills the surface of the wet paint to the saturation point on a humid day causing your paint to blush, or capture microscopic drops of moisture in the drying paint.

Several things can be tried to reduce or eliminate the problem.
1) Reduce the solvent content to reduce the chill effect of the evaporation
2) Spray in an air conditioned space with much lower humidity
3) Raise the temperature of the paint/thinner before spraying so it doesn't need to absorb as much heat from the surrounding air
4) Raise the temperature of the surface to be painted (see #3)
5) Wait for a day with lower humidity

Yea its humidity. I've found that some times you can buff it out and it will look fine. It works for clear coats. Anyways the only real option you have is to spray and immediately get the body back inside or into a dehydrator. I found that duplicolor paints are extremely sensitive to humidity. Tamiya paints are "stronger" in this sense.

Not sure if you can get 'anti bloom' thinners where you live, but if you can, thin with those instead of ordinary thinners and it should stop the blooming/blushing whatever you want to call it from happening.

I meant to say "bloom". Steve Noble has the term right.

Steve, Is the "anti-bloom" thinner a retarded evaporation rate/dry time?

The reason I ask is I've noticed the auto jobbers in my area carry reducers rated for different temperatures. I assume the difference between formulas is evaporation rate. Just thinking out loud here: If the higher temp rating were used to slow evaporation it should reduce the chance for bloom all other things being equal, right?

Steve, Is the "anti-bloom" thinner a retarded evaporation rate/dry time?

Yes, the anti bloom thinners are slower drying than conventional thinners. The 'blooming' is usually due to solvent not evaporating quickly enough from the paint surface, normally in a cold or humid environment. This is why most paint shops are heated to 20 degrees C, but spraying at home it's not always practical to be able to do this. Spraying on a warm, dry day will help, as will placing the parts in a dry booth or dehydrator after spraying. Blooming can also be a real problem on colder days. Again keeping the spray area warm and, in the case of spray cans, warming them up before use will help. As will the use of the dry booth or dehydrator again.

Too much/wrong thinner. 300% is crazy.

Just noticed about the 300% thinner ratio. Depending on the paint you shouldn't need to thin it that much. I use mostly Zero base coats now and they are supplied pre-thinned for airbrush use. However I do thin them some more for best results. If you thin to the consistency of milk then this is usually about spot on for spraying and you get good coverage as well. You can maybe thin the final finish coats a touch more once you've got a good base of the colour down, but still only a touch.

i live in illinois i used to have the problem i just put a dehumidifier in the room

3/1 thinner ratio for decanted Tamiya? Actually, that seems perfectly sensible to me. After decanting it, TS loses a great deal of its solvents- especially if you're leaving it uncovered to let the propellant outgas. The amount of solvent that outgasses in the process depends on time, ambient temp, and ambient pressure so your milage is likely to vary. But by the time I'm airbrushing decanted TS, I'd say I've added back at least 2/1 thinner. If it takes more, I give it more.

What color is this happening with?

My guess is also that it's humidity. I would try spraying lighter coats, and/or leaving more time in between. This may 'trap' less humidity as you're spraying.

I apologize for the long delay in response, as I had a family emergency and I've been out of town.

This is happening on mostly darker colored cars, I have reviewed all of the responses and I appreciate them VERY much. I did recently install a window air conditioning unit in my garage to alleviate the humidity problem and I have also, not thinned my paint as much. I'm working on shooting thinner coats of paint. I do have a dehydrator and I'm wondering if I should dry each coat in the dehydrator prior to shooting the next coat or would it suffice to just shoot each coat waiting ??? minutes between them and then dehydrate the car.

Thanks for the great help and many very logical responses they have helped me considerably.