Difference temperature makes.

Barry

Barry

Paint Fanatic
Staff member
Gel.jpg There's a rule of thumb that if a paint is made to work at 70 degrees every drop of 10 degrees will result in a 15% difference. so say gel time is set at 300 at 70 and now it is 60 the gel equivalent would now be 345 if humidity stays the same. Net result, the product is slower by 15% and if 80 degrees the product would be faster by 15%.
The cold has hit GA with snow and we made a batch of 5000 yesterday for testing last night and will fill today.

I run two gel tests one in the manufacturing part and one in kitchen, why as I show you the results that will explain. We keep all areas 70 degrees 24 /7 so iso's and polyols don't thicken up but the manufacturing part has 24-foot ceilings so humidity is always higher than in the office and with the cold it was down to 68 degrees this morning in the higher ceiling part.
So here are the test results.
Kitchen 239 gel (no reducer as that extends the gel) 72 degrees and 30% humidity.
Shop 265 at 68 degrees and 70% humidity
Old math or new math that is a 10% difference+.

Just thought this might be interesting.
 
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I do mobile work and this was my yesterday. Air temp was around 25 with 15mph wind. Black panel, temp varied by 60deg (30-90) from shade to sunlit areas. Used shortwave lamps to equalize. Used universal with regular and slow activator mix. First coat flashed(no tackiness) in about 5 min. Came out very nice. Who would have thought using a slow in winter? Don't know if anyone finds this interesting but I was shocked.
 
Humidity- how does say, every rise or fall of 10 vari gel & what is baseline humidity level?
South FL is quite moist all but 2 months.
edit- thanks for all your knowledge & work Barry.
 
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EddieF said:
Humidity- how does say, every rise or fall of 10 vari gel & what is baseline humidity level?
South FL is quite moist all but 2 months.
edit- thanks for all your knowledge & work Barry.
Click to expand...

Eddie, there is no magic guideline for humidity as way too many variances to contend with.
From the speed of activator to gel time of product used from primer to clear.
Here is why High humidity at different temperatures act differently, the humidity slows the solvent evaporation point but the tin in part A is working overtime trying to force the moisture to the iso to cure the product. So slow and more flash is always the best choice.
 
I remember 2 yrs back having issues & mixed small cups of uvc unactivated with water, alcohol, ect to see effect.
50/50 mix of water & uvc gelled. Alcohol too. Cheap laquer thinner globbed up gun when rinsing it, 1st ingredient was alcohol. I learned some.
 
Which also must mean wet air feeding gun will screw flowout, thickening clear as it shoots out gun.
 
What humidity levels are the dry times estimated at? When you manufacture your paints and recommend (just making up a number) a 30 minute flash time, is that at 50% humidity? Or 10 or....?
 
Most paints are made to work at 70 Degrees with 35% humidity.
This means you can paint in Georgia 10 minutes a year; LOL
 
The 30-minute flash has nothing to do with the temp.
The reason we say that is because of the higher solids of our clears it goes like this:
Insurance work- spray wet coat and spray 2nd coat in 10 minutes or longer as they just do 2 coats.
In restoration or custom painting where 3 or more coats are being applied, than wait 30 minutes between all coats to avoid solvent pop.
 
I wasn't necessarily speaking of clear, just generally curious at what humidity level they are measured at, your other post hit the nail on the head!
 
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