Painting in seriously, seriously, HUMID climates

[Hawk312]

I know there have been posts previously regarding this issue. And I have experience battling this for the last 25 years or so of building. 

But I have recently moved to a very humid climate. Just for example, the dew point will be close to 80 degrees today, and has been since early spring. A day where the dew point is in the lower 70s is rare. So, when I was up north I would spray in humid weather and I would get fogging, etc....everything that you would expect painting in humid weather. But it wasn`t a big deal if I was patient and waited for it to gas out. I have even had finishes that were supposed to be black but looked like gray primer immediately after spraying clear, but dried and polished to a deep, mirror shine. 

I am trying to spray my 1/12 `73 Trans Am I am currently working on, and water droplets are forming on the surface while I am spraying. Needless to say, the paint is dull, which I can live with and polish out. I had this problem up north. But I also noticed that clear from parts I sprayed 3-4 weeks ago, after a cut and polish, simply stay dull no matter how much elbow grease I put into it. 

I have tried spraying day and night, indoors and out, even in climate controlled area, with the same results. What are you guys doing that live in tropical climates? I noticed some mention of food dehydrators, but that gets interesting when working in 1/12 scale.  I`ve also seen people buying dehumidifiers, but I would like to know if this has been effective or of there are any issues setting one of these up in, say, a garage. 

Thanks!

[Ace-Garageguy]

Even painting REAL cars can be a serious problem in hot, humid climates. One summer here not too long ago, all the body shops were painting in the middle of the night and using the maximum amount of retarder in the paint to combat solvent-popping...which can NOT be polished out, and requires a strip to repair correctly.

Are you airbrushing, or rattlecan? If airbrush, moving your water trap AWAY from the compressor will allow the compressed air to cool more prior to going through the trap, and will have much less water vapor in it as a result.

Also, what clear are you using? There are some that are relatively insensitive to humidity-blushing, and some that will stay milky-dull almost forever. If you're airbrushing lacquer, retarder (from the body-shop supply store) can be used to minimize the blush reaction too.

A dehumidifier in a fairly well-sealed room will also be of great help, but you're going to need a hygrometer to gauge its effectiveness, and try to do your spraying only when the humidity is under about 60%, and air temps under 80F.

Edited September 29, 2018 by Ace-Garageguy

[Hawk312]

Thanks Ace for taking the time to post all that detail!

I using Duplicolor from the can, just because the base coat had to be a specific paint code. I think that is one of the more susceptible brands....I haven`t had the issue *as much* with Model Master or Tamiya lacquer. I am a little worried about the Duplicolor base "pulling back" from the edges though if I try one of those on top. Maybe I just need to break down and buy an airbrush for this?

 

[Fat Brian]

I have the same problem with Duplicolor, it blushes so quickly I'm not even finished with the coat before where I started is flat. Tamiya and Model Master both have a little longer working time. For those paints I dry them in a warm oven for a few hours to let the paint set up.

[Casey]

21 hours ago, Hawk312 said:

I`ve also seen people buying dehumidifiers, but I would like to know if this has been effective or of there are any issues setting one of these up in, say, a garage. 

Well, provided the space you use it in us well sealed from the humid air, yes, it will effectively remove the humid air.

Why not invest in a dedicated indoor spraying area so you at not at the whims of Mother Nature? If it's that humid where you now reside, I would guess you have central A/C?

Edited September 30, 2018 by Casey

[Miatatom]

Like Casey said, a dehumidifier will work, that is, if your garage is finished in. Probably won't work if it's not. I spray in a room in my basement. My dehumidifier keeps it at about 50% humidity all the time.

[restoman]

If you're using rattle cans, there are a few little tricks to try, but it's a BLAH_BLAH_BLAH_BLAH-shoot.

We regularly get 75% and higher humidity levels in the warmer months here. Here are a few things I've learned over the years:

Warm your spray cans a bit. I use an old electric frying pan, set at it's lowest setting. Keep and inch or two of water in the pan, let the can warm for at least 20 minutes before use, and set the can back in the water between coats. Don't forget to dry the can off before going near whatever you're painting.

Keep some air moving in your spray area. Not enough to move curtains but enough that you can feel a very slight breeze on your face. Of course, your spray area and the area on the supply side of the air needs to be clean...

I like to spray at first light. The air is typically calmer and cooler. Cooler means less moisture.

Let whatever you're spraying sit wherever you're spraying for at least  20 minutes. Moving a cool object into a warm spray area is not a good idea when you're trying to defeat moisture.

Wear latex or nitrile gloves. Oils from your skin are death to a paint job, and it's a much bigger problems when your skin is moist.

Take your time. Let every coat off-gas before loading on another. Humid air will always slow down flash times and off-gas windows, and plays heck with through-cure times.

Hope some of this helps. I was a bodyman/painter for over 30 years and humid air is always a challenge, no matter what you're doing. I've sprayed in mid-90% humidity levels in a cross-draft booth with no air dryer... and had good luck, but it would literally take up most - if not all - of an entire day. Those were the days I really felt like I was under-paid... and I was self-employed!