Higher humidity and urethane
07-02-2015, 02:44 PM
#1
Melting Slicks
Thread Starter
Higher humidity and urethane
After 10+ years of prep, I am finally ready to start painting my '64. I have built a spray booth with a fan and lighting. My weekend goal is to paint the doors and hood to start. I will be using PPG DCC acrylic urethane as a single stage in ermine white. Typically, this time of year in my area of southern CA we have night and morning low clouds and sunny days at about 80 degrees and 30% humidity. Currently, we are having a monsoonal flow with 80-90% humidity with 80 degrees and only slightly better conditions predicted for the weekend. My spray set up has 2 desiccant driers(one is the large Speedaire nearly 3 feet long) and 50 feet of copper pipe to cool the air prior to the desiccants; certainly not what a pro would have. With both DUB and Porchdog in the high humidity areas of the country and others with experience, I hope you will chime in with any advice, primarily if I should wait for better weather. As always, thank you in advance. (I will post photos afterwards if I don't commit suicide if disaster strikes
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07-02-2015, 06:43 PM
#2
Race Director
OK....STOP and think about this. 10+ years of hard work. SO WHY rush it.
YES...I have to paint in bad humidity conditions...but trust me....I do not paint in the rain. I have a temperature gauge and humidity gauge in my booth and I prefer to have the humidity as low as possible.
NOW...in my paint system I can use a thinner/reducer to compensate for high temps or high humidity....thus...my basecoat stays wetter... longer....thus allowing the moisture in the air that is blowing across it from effecting it.
I have had a Corvette in the booth ready to be masked off and shot and it has sat there for days until the weather got to a point where I felt more comfortable in the humidity and temps were better.
I know you are shooting a single stage. And generally they stay wetter longer....so moisture should not be an issue.
Hopefully 'porchdog' will comment because he shoot nothing but single stage as I understand.
You can also use a mirror and a pencil blower and blow your compressed air onto the mirror and see if it fogs up or you see moisture droplets on it. And do not fool yourself. turning on your compressor the first time in the morning and immediately checking for moisture is not the same and the 20th time the compressor has come on during a paint job....right???
DUB
YES...I have to paint in bad humidity conditions...but trust me....I do not paint in the rain. I have a temperature gauge and humidity gauge in my booth and I prefer to have the humidity as low as possible.
NOW...in my paint system I can use a thinner/reducer to compensate for high temps or high humidity....thus...my basecoat stays wetter... longer....thus allowing the moisture in the air that is blowing across it from effecting it.
I have had a Corvette in the booth ready to be masked off and shot and it has sat there for days until the weather got to a point where I felt more comfortable in the humidity and temps were better.
I know you are shooting a single stage. And generally they stay wetter longer....so moisture should not be an issue.
Hopefully 'porchdog' will comment because he shoot nothing but single stage as I understand.
You can also use a mirror and a pencil blower and blow your compressed air onto the mirror and see if it fogs up or you see moisture droplets on it. And do not fool yourself. turning on your compressor the first time in the morning and immediately checking for moisture is not the same and the 20th time the compressor has come on during a paint job....right???
DUB
07-02-2015, 07:42 PM
#3
Melting Slicks
Thread Starter
DUB:
Thank you for your reply and I do not want to rush this. Rain in July here is nearly unheard of. What humidity range do you find to be acceptable? I have medium and high temp reducer for the project so I am set there.
Thank you for your reply and I do not want to rush this. Rain in July here is nearly unheard of. What humidity range do you find to be acceptable? I have medium and high temp reducer for the project so I am set there.
07-02-2015, 08:07 PM
#4
Race Director
50% humidity....if not less. I prefer less....if I can wait.
It has been so long since I have shot that type of PPG paint....I honesty can not remember how it reacts when a different grade of reducer is used.
I know in the NEXA system I use how my basecoat will react.
If you have any concerns/worries...you might want to possibly call PPG at 1-800-647-6050 and get into the tech dept by listening to the prompter. I know that they might just read off a sheet ....or you may actually get lucky and talk with someone who actually shoots the stuff and really knows it. IF NOT...contact the local PPG rep and talk with him/her. Not trying to make you paranoid...just trying to cover all possibilities due to the TIME you have in this WARRANTS it.
DUB
It has been so long since I have shot that type of PPG paint....I honesty can not remember how it reacts when a different grade of reducer is used.
I know in the NEXA system I use how my basecoat will react.
If you have any concerns/worries...you might want to possibly call PPG at 1-800-647-6050 and get into the tech dept by listening to the prompter. I know that they might just read off a sheet ....or you may actually get lucky and talk with someone who actually shoots the stuff and really knows it. IF NOT...contact the local PPG rep and talk with him/her. Not trying to make you paranoid...just trying to cover all possibilities due to the TIME you have in this WARRANTS it.
DUB
07-04-2015, 03:52 PM
#5
Drifting
one problem you can run into with high humidity is ISO clumping . it will look like dirt in the finish . urethane is effected different than old lacquer and enamels . slow them down enough and most of the blush would come out. even another coat would help. but urethane will kick off weird in humidity . like dub i shoot for 50% or less.