Painting in outside temperatures-- Need some advice

Question: Others have urged that the secret to flawless finishes is temperature controlled painting. That is, some have gone as far as building a small heated, flood light controlled paint booth out of a wardrobe box.
What I want to know is when the paint label says "paint should be applied in the 65-90 degree range," are they talking about the ambient temperature outside, or the temp of the paint, or of the object being sprayed or all of them.

Some have suggested that they mean only that the paint can itself should be in that range. Others say that they paint spray drops to the ambient temperature outside the can as soon as it is sprayed, and so it will freeze or clog if you attempt this below the recommended range.
Others say, screw it, go spray a light coat as long as the rocket is coming out of a heated house, the paint is warm, and the air temp is above freezing.

What is the truth of the matter?

Funny side note: I have selected a spray can that is labeled "Non-gloss black" for a flat finish. Reading the back of the can, the first thing is says is that this is a high gloss paint. Duh! Do they not read their own labels?

My experience with "good" results is keep paint warm. Spray in cold, then bring it to warm to cure.

Ideally the temp on the can refers to ambient. But, you don't want either the paint or the surface very far from that target temp either.

Cold spray cans tend to dribble rather than spray.

Just my observations.

I tried this today and got away with it. I put the paint can (Rust-oleum paint with epoxy) on top of the heat duct that comes right out of the basement furnace. The can got nice and toasty. I shook the can inside the house and when I was ready, I quick went outside and sprayed a light coating. I quickly brought the model back inside to cure in the basement workshop with the door closed. The smell of paint is strong. We are in a cold wave here right now like a lot of the nation. Apparently, this method worked. I may try again tomorrow.

Kirk G said:

Funny side note: I have selected a spray can that is labeled "Non-gloss black" for a flat finish. Reading the back of the can, the first thing is says is that this is a high gloss paint. Duh! Do they not read their own labels?

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Labels are pretty much universal... they have it written by a technical writer or whatever ONCE and then use it on all their products, regardless of what's in the can-- unless it's something with COMPLETELY different properties (like the differences say between lacquer and enamels) and then they'll USUALLY (but not always) modify accordingly. Some brands keep it "vague" enough they don't bother...

As for the temp ranges, the "best" application job and finish usually comes from the can, contents, object being painted, and air all being in the recommended range. Personally I like to either keep the cans in the heated house, or if they have been outside, bring them in and leave them sitting in a bowl of hot water for about thirty minutes to warm up the contents. Warm paint flows easier and smoother, atomizes better, and of course adding warmth to the can via a warm/hot (not scalding or boiling) water bath of the can raises the heat content of the can and propellant, meaning higher spraying pressure (better atomization and a wider spray pattern). Warm paint also "flows out" better on the surface.

If I had to rank it, I'd say having warm paint is the most important, followed by a warm surface, and ambient temp the spraying is done in last. I've painted some rockets in freezing weather outside with good results, so long as the paint is thoroughly warmed and the rocket is staying indoors in a warm house. IOW, just step outside to physically spray the stuff onto the rocket, then back inside. While it's true that the paint, once atomized into extremely small droplets, have much higher surface area per volume of the droplet and therefore lose heat much quicker to the environment, they are only airborne for a fraction of a second or so, and then land on the warm surface and should flow and merge with other paint droplets. Of course the thin film of paint has also got a huge surface area compared to its mass, and will chill quickly, so if it's well below the 'recommended' temp range, minimizing exposure to those temps is always a good idea (the colder it is, the less time you want to spend outside spraying anyway). Basically as soon as I've shot a coat on, I bring everything back inside to warm up.

Basically, the recommended temp ranges are to 1) avoid blushing or fogging of some kinds of paint, from excess humidity and such, 2) promote drying/curing. The cooler it is, the longer the paint is going to take to outgas and "cure". Paint a rocket with a slow-drying enamel in 30-40 degree weather and leave it in an unheated garage, and the paint will still be "soft" after a week sometimes. Bring it in to a 70 degree house and it'll be dry MUCH faster. Basically the warmer/hotter the painted item is sitting in, the faster it will dry. Hence the "warmed paint booths" or whatever... heck I've even put rockets in an old vehicle in the summer, but be careful of direct sunlight on the painted surface-- I've had the paint bubble because of that! (too hot!) A "hot box" will drive off the volatiles faster and help the paint dry faster.

If it's REALLY a cold area (freezing or below) then IMHO you're flirting with trouble trying to apply paint in those conditions. It may work, it may not... kind of a gamble. Things will "cold soak" very quickly the colder it is... all depends on how low the temp is and the heat content of the objects (paint and being painted) are and how fast they conduct heat to the environment.

Later and hope this helps! OL JR

I have heated garage , so paint and rocket is warm when taking outside to spray , I do it quick and get both right back inside to dry

cardboard kits drying last march

aerostadt said:

I tried this today and got away with it. I put the paint can (Rust-oleum paint with epoxy) on top of the heat duct that comes right out of the basement furnace. The can got nice and toasty. I shook the can inside the house and when I was ready, I quick went outside and sprayed a light coating. I quickly brought the model back inside to cure in the basement workshop with the door closed. The smell of paint is strong. We are in a cold wave here right now like a lot of the nation. Apparently, this method worked. I may try again tomorrow.

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Thanks to all who have given their advice.

The worst behaving can has been flat white primer (Krylon) that I got from Lowes. It seems to have real problems coming out of the nozzle consistently. But I did get it to spray more evenly after scraping away build up on the safety lock press-nozzle.

Aerostadt-- be careful about putting your pressurized can on a heating element. I'm worried that setting on top of the first vent away from the furnace might be too much heat! I'd hate to hear about a paint bomb going off in your house!:surprised:

michigander said:

I have heated garage , so paint and rocket is warm when taking outside to spray , I do it quick and get both right back inside to dry

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+1 to this.

dixontj93060 said:

+1 to this.

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Sure, also I am thinking that it might degrade the paint that has epoxy. I did this again today and it worked with the outside air temperature at 20 Deg.F. I only put the can on the vent for about 10 to 30 minutes. After spraying I put the can back in the basement workshop.

Here is a couple things that work for me. Paint/ Paint can at near room temp--surface temp of the object-warm---put it in the sun!! and out of the wind--after you spray it, bring it inside to room temps to cure--you will blush otherwise---Oh Yea, do a few lite coats first and let them tack off and do a final colour coat/gloss coat--takes some practice but works--H

My trick:

Keep the can in hot water (tap hot. Not boiling)
Get everything ready (boots, warm clothes, clear path to the garage/painting area, project, paint)
Go out and head to the shelter.
As humanly fast as possible paint your project with your paint of choice (Me: Rustoleum metallics) in quick even strokes.
Let the project sit for about 30 minutes, then bring indoors.

So far this has worked fairly well. Lacquers will blush a bit, but they tend to clear and return to normal. Oil based paint works, but rather slow to set up. Epoxy Appliance paint will take the rest of the winter months to set up and your project might be ready in the mid-springtime. ( )

Both paint and the surface to be painted should warmed. Rocket to room temperature and rattlecan soaked in tap water hot enough to be comfortable...too hot is too hot.

Spray in sunlight if you can and bring the rocket inside as soon as you can provided SWMBO allows it. If not, your results may not be optimal.

via Forumrunner/GS4

michigander said:

I have heated garage , so paint and rocket is warm when taking outside to spray , I do it quick and get both right back inside to dry

cardboard kits drying last march

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+2 to this.

The best paint finish I ever got was when; I painted outside in 90 degree heat with low humidity.
Second best was in a heated garage.
Be very careful when painting inside!
Make sure you use the proper spray mask or have a vent hood.

JD

I'll paint well below freezing outside, if it's calm, and bring the rocket inside for drying between coats, with the same caveat that old_dude mentions.

I've painted a few rockets at -20 to -30F. Make sure your paint is warm, then just go outside and paint as your normally would. An issue at temperatures that cold is the paint will pretty much immediately freeze on the rocket so you have to be careful in keeping the thickness even as it will not even out very much. Lots of light quicker strokes help as well with with the keeping paint can slightly closer than you normally would. Keep your coats as thin as possible while still getting full coverage. Do a few extra of these thinner coats than you normally would at regular temperatures.

Then bring the finished rocket back in to a heated room and the paint will settle and even a bit on the surface as it thaws out. Got pretty good results overall, granted I wasn't exactly going for pretty, I just wanted the rocket florescent orange so I could find it again a bit easier.

In winter I will step ouside and give it a good going over, but first I will run hot water over the can and shake it ocasionaly untill it is nice and warm, and be sure to wipe off the water, especialy around the nozzel.