Weather for outdoor painting ?

[Brockport Bill 2,239]

the rustoleum paint cans suggest  temps 55 plus and humidity below 55 %. There are a few days coming up with close to those thresholds  -- but not perfect -- anyone know which is more critical -- the temp or the humidity?  - if one is in margins but the other not?  i can wait for warmer temps and proper humidity levels but am eager?

[ebinmaine 77,634]

The BBT aka Paint Department is in the habit of spraying outside and immediately bringing the pieces INSIDE to dry.  

 

 

 

[SylvanLakeWH 30,719]

 

I've had decent luck with that technique, but I ain't no BBT... 

[Ed Kennell 45,160]

I usually bring my paint and parts inside for a day before painting to get everything up to 70*.

[AlexR 2,674]

I have been painting Rust-Oleum in the just below recommended temperatures and its been ok the biggest thing I noticed that causes problems is if the metal you are painting is pretty cold such as colder earlier in the day or the night before and hasn't warmed up enough it doesn't stick very well and gets runs easily. (If possible get the metal as warm as practical, the cans of paint also need to be kept warm) Also it takes much longer to cure.

 

As to your question I would say it's definitely better to wait for both temperature and humidity to be ideal but humidity can cause a disaster if it's too high and the metal is sweating. 

I would not paint major sheet metal in less the ideal especially the hood, but the smaller parts you will probably be ok if you aren't looking for a perfect paint job. If you want the paint to be really good low humidity and 70° will make it easier 

Edited yesterday at 09:24 PM by AlexR

[Easton Rich 1,056]

@AlexR said it best. Don't get impatient and paint while its cold. 2x the work. Make sure you lay thin coats if you're in the lower temp range. Just my 

[kpinnc 17,399]

2 hours ago, ebinmaine said:

The BBT aka Paint Department is in the habit of spraying outside and immediately bringing the pieces INSIDE to dry.  

 

 

I do the same. 

[ri702bill 11,454]

Agreed - it still takes a month or so for it to cure enough for assembly...

And use a trick from my old building model car days from 50 years ago. Warm the paint can in a pan of hot tap water. It raises the pressure in the can - gives a better finish. And it flashes off faster between coats....

 

[ebinmaine 77,634]

14 minutes ago, ri702bill said:

month or so for it to cure enough for assembly...

 

Our experience shows longer.  

 

Assembly.... very carefully.  A few days.  

 

Cured?   Man..... 2, 3 months or more. 

 

Even then don't expect auto paint type durability.  

[Brockport Bill 2,239]

wow - - great insights for the painting --  when i have been on the temp margin I have been bringing the item inside the garage 55-65 degrees plus turning on space heater to warm steel surface -- also I do warm the paint can in front of the space heater - never did the warm water pan tho as suggested ----- Always wondered tho if the paint "droplets" from spray actually get "cold" or effected by air humidity between can and before the spray hits the metal surface? 

For the humidity i have only marginally gone above 55% -- maybe 60-65 ish  but never higher -  However, per other comments above i have never tempted below the margins for anything I wanted to look nice like a seat pan or hood -- Not so concerned for a plow type project

[kpinnc 17,399]

6 hours ago, ebinmaine said:

Even then don't expect auto paint type durability.  

 

Given this alot of thought lately. Automotive paint is nice and holds a shine but can be quite brittle. What will make a scratch on many surfaces will chip on Automotive paint with hardener. 

 

Rattle can paint is softer, but most scratches are just that. With some work they can be repaired. I painted the V14 with rustoleum + hardener and it still is a bit rubbery several months later. I'm starting to like the durability of it. 

 

One thing to note: if your paint gets exposed to long term direct sunlight (think shed with open sides), rattle can won't hold up as well as Automotive. 

 

All my machines do some work. They just get exposed to a tougher life than what my truck gets. They get dirtier and far more scratches. At least I can make a decent (sometimes) repair on my tractors. 

[953 nut 64,445]

High humidity will slow the process of "offgassing" where the VOCs (volatile organic compounds) in the spray can become trapped in the pint causing it to blush.