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I just finished stripping a ton of Wood Elves and Tyranids and I'd like to get them ready for painting. I use acrylic spray paint (usually a light gray) instead of primer, but unfortunately it's been super cold, it being January and all. Do the cold temperatures have any adverses effects on spray paints? It's about 30 degrees here.

Yes the cold can cause uneven spraying, uneven drying, paint cracking, and all sorts of nasty effects. Humidity is even worse. From my own experiments I've found that 10C is the absolute coldest where I can spray without bad effects being noticeable.

Remember that when a gas pressure suddenly drops (wich is what happens when using spray paint) its temperature will also decreases.
Two common exemples of this are snow canons on ski runs, or simply if you use spray deodorant you can feel that it's cold. That's physics.


So yeah, spraying when it's too cold is risky. It might work. But it most probably could cause some annoyances as stated above.
I would avoid to spray under 10°C too.

You can spray in any weather, just step outside, spray, step back in and lay it down to dry (inside)

Unless its actually lashing down with rain (then use an umbrella too) theres not much to go wrong. Dust storm might cause a problem.

Only if its also crazy humid inside then you might get problems.

Here is a alternative way to spray indoors, get a large shipping box with flaps turned side ways and some newspaper underneath as prevention measures; set models halfway in the box and spray away.

Get yourself a paint fumes mask if you're gonna do it indoors though, otherwise you could mess up your lungs.

Roommates might take issue with spraying inside. Could probably spray on one of the warmer days (~50 degrees F) and bring them inside to dry.

 TheSilo wrote:
Roommates might take issue with spraying inside. Could probably spray on one of the warmer days (~50 degrees F) and bring them inside to dry.

Thats pretty much the best way to go. You can do it even in the cold really. I've seen it done during snow fall.

one other good thing to do are to warm the can up. Run it under the hot tap, shaking it lightly as you do until the can stays warm to the touch. (the heat will go as you shake it quite quickly to start with) - dont make it too hot to hold, just warm is plenty good ~ the can explodes above 50C or so (something like that)
This helps to increase the pressure inside the can and to lower the viscosity of the paint making it mix better and spray better. The slightly higher temp also plays to advantage against cold weather spraying.
Higher pressure helps you with laying down thinner coats (that would have a lot of solvent in that struggles to evaporate in the cold) as the paint atomizes better when leaving the nozzle.

My personal approach is to spray inside my shed, and lay them down in there for 5-10minutes to allow the main part of the solvent to come off, and then to bring them indoors. They still give off a bit of a smell at this point but its nothing on actually spraying inside. Leave them at the opposite end of the house to where everyone sits even better if theyve all gone to bed and wont even notice the smell downstaris for a few hours, then my minis are nicely cured for painting the next day.

I'd avoid humidity more than cold, but anything below ~40 degrees is risky. You can always test with a small piece.

Still... there are options, especially for smaller lots. You can spray in a doorway, so that it's warmer, but well ventilated. I used to use the fan on my stove to help keep the fumes down after I brought the fresh sprayed models in.

If you need to spray a large batch, reach out to people in your community. Somebody has a basement or garage or someplace you can use. Bring your models, some stuff to prime on, your cans, use their space, give them a six pack for their trouble, and there you go.

I've 'primed' minis with spray paint in sub-freezing temperatures with no ill effect. The key is, as HairySticks mentioned, to keep the can warm. If the contents are within the range of their optimal conditions, ambient temperature matters little - it would need to be so hot that the solvent immediately evaporated or so cold that the atomized paint froze solid in the air to make spraying impossible.

If I need to spray aerosols in winter, I prep my models, give the can some attention (alternating shaking and running under a hot tap until thoroughly mixed and warm), spray outside, then pop them in the bathroom with the vent fan on to finish off-gassing. Once they've lost most of the stink, they come back into the hobby room to finish curing. Easy as anything, just takes a few extra minutes of prep.

Neither temperature nor humidity need ruin your priming job. Simply store both models and paint can indoors so they are the same temperature (and warmer than outside). Go outside, prime quickly and bring them back indoors to off gas and dry. Sticking a fan facing outwards near a window helps keep the smell down.

We might have found the problem for 99% of the bad primer jobs out there here guys.

Storage of the can.

Hands up anyone who has problems with primers that stores them outdoors?

Hands up anyone who always primes perfectly who keeps it indoors and/or warms the can prior to spraying?

We already knew the cause of 99% of aerosol spray (primer or varnish) issues - the user.

 oadie wrote:
We already knew the cause of 99% of aerosol spray (primer or varnish) issues - the user.

quoted for the win!

In seriousness though, We do see a lot of what happened with my primer threads. I have a feeling that the issue is often over analysed an its as simple as warm your can up and shake it better, and allow to cure at room temperature.

I cant even remember the last time I had a bad spray job that wasnt caused by the paint running out half way through the job (admittedly Spraying paint has been a bit of a hobby of mine though - trained in car body work - I've successfully sprayed 2K paint in the winter without an oven booth to set it in 90mins). And frankly I spray in any conditions the UK midlands can throw at me ~ so thats ranging from a medium heat / cold range, and a decent bit of humidity. We never particularly see extreme heat or extreme cold that some countries may get (although we will moan and tell you otherwise - when its raining i wish it was sunny, when its sunny... its TOO F*CKIN HOTT!!)

I live in area that got -18 F last year. I keep my spray paints inside & usually right before spraying in the winter I'll set the can & minis near a heat source. Then once they've been sprayed they go back in front of said heat source.

 Todosi wrote:
Neither temperature nor humidity need ruin your priming job. Simply store both models and paint can indoors so they are the same temperature (and warmer than outside). Go outside, prime quickly and bring them back indoors to off gas and dry. Sticking a fan facing outwards near a window helps keep the smell down.

This is what I do.

Another alternative is to use airbrush primers, the vallejo surface primer is just amazing stuff.

one note: your starting thread sounded like you are not using an actual primer. primer is not just a base coat of a another paint.
Primer is formulated differently - it adheres better than normal paint, and has a more "rough" surface to it, so other paints can stick to it.

There are TONS of threads on basic spray primers if you are looking for a good one.