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Building Tips and technical articles. => Paint and finishing => Topic started by: Larry Renger on August 03, 2017, 07:12:28 PM

Title: Maximum humidity?
Post by: Larry Renger on August 03, 2017, 07:12:28 PM
How high can the humidity be generally for blush free spraying? Think spray can paint, not retarder laced dope.

I didn't think it mattered from a rattle can until one model turned white. Guess the paint can pick up plenty of moisture in a foot of travel and drying time.  HB~>

Also surprised to find that it was a problem with enamel, not just laquer.

We live and learn! Now to learn what I need to know.  H^^
Title: Re: Maximum humidity?
Post by: Target on August 03, 2017, 07:57:28 PM
We are way above normal hum-did-dity here right now. If it happened in the last few days, you can blame it on the hurricane south of here.
Title: Re: Maximum humidity?
Post by: Paul Smith on August 04, 2017, 07:31:48 PM
Randolph recommends under 50% if you care about blush.

Their retarder (a slow-drying thinner) helps reduce blush if you can't wait. 
Title: Re: Maximum humidity?
Post by: billbyles on August 05, 2017, 12:18:23 PM
Randolph recommends under 50% if you care about blush.

Their retarder (a slow-drying thinner) helps reduce blush if you can't wait.

Larry was talking about spray can paint so the available thinner would not be applicable here.
Title: Re: Maximum humidity?
Post by: Tim Wescott on August 05, 2017, 12:36:44 PM
How high can the humidity be generally for blush free spraying? Think spray can paint, not retarder laced dope.

I think it would vary widely by brand.  Someone that routinely sells into humid areas might put retarder into the mix, to prevent blushing.  Someone who routinely sells into dry areas might make a fast-dry mix, either for economy or to reduce drying time for the consumer.

You're kind of at the mercy of the paint supplier.  I'd try looking at their web site to see if they have recommendations, but I wouldn't stake my enjoyment of life on finding an answer.
Title: Re: Maximum humidity?
Post by: Brett Buck on August 06, 2017, 12:23:46 AM
We are way above normal hum-did-dity here right now. If it happened in the last few days, you can blame it on the hurricane south of here.

     I wondered about that, it has been quite sticky by local standards for the last few days, it even sprinkled rain in the morning on Thursday.
   
   Brett
Title: Re: Maximum humidity?
Post by: Randy Powell on August 07, 2017, 01:46:45 PM
I have a barometer in my shop. I've shot as high as 70% without problems, but you are in the range at that point. Generally anything above 60% without retarder or at least extra thinner is going to be a problem. When it gets on toward 80% (which it is a lot around here), you can hit it with retarder and extra thinner and cross your fingers. It might be OK. Maybe. Anything above that and it's just not worth it.