Painting in cold weather!!

[Scott1984]

Does any one have any advise on painting/priming models in the cold. It is about 8 degrees right now. I do all the railroad stuff in the garage so it is not ideal. Just thought I would ask to find what you guys do. I use an airbrush for priming the models with acrylic primer. Thanks!!

[peteski]

Many (water-based) acrylic paints warn to protect them from freezing (it  will destroy the paint). That was back in Floquil Polly-S days. Not sure if modern water-based paints are also that sensitive to freezing.

Solvent-based (stinky) paints are ok in cold temperatures.  Eight degrees is a bit nippy. Hopefully inside the garage is a bit warmer than that.

While I have not painted when it was that old, cold temperatures usually mean the air is very dry and static electricity can easily build up. That might cause dust to stick to the plastic painted surfacres, messing up the paint job.   I usually have problem airbrushing in the Summer when it is hot and very muggy (humid).  The humidity can cause blushing of the painted surfaces.  Not a problem in the winter.

Of course in the cold temperatures paint will take longer to dry.  I use an old food dehydrator to speed up drying time.  Its internal  temperature is between 110-120 deg. F.  Works really well.

[Scott1984]

Many (water-based) acrylic paints warn to protect them from freezing (it  will destroy the paint). That was back in Floquil Polly-S days. Not sure if modern water-based paints are also that sensitive to freezing.

Solvent-based (stinky) paints are ok in cold temperatures.  Eight degrees is a bit nippy. Hopefully inside the garage is a bit warmer than that.

While I have not painted when it was that old, cold temperatures usually mean the air is very dry and static electricity can easily build up. That might cause dust to stick to the plastic painted surfacres, messing up the paint job.   I usually have problem airbrushing in the Summer when it is hot and very muggy (humid).  The humidity can cause blushing of the painted surfaces.  Not a problem in the winter.

Of course in the cold temperatures paint will take longer to dry.  I use an old food dehydrator to speed up drying time.  Its internal  temperature is between 110-120 deg. F.  Works really well.

Thanks for the info!! It is warmer in the garage, not sure how much though. I will get a thermometer out there to check. Probably not the best conditions to be priming some stuff. Thanks again for your help!!

[wazzou]

I honestly would just wait. 
60+ degrees is about my threshold for where decent work can be accomplished.

[Scott1984]

Yup, that is what I am going to do. Just checked my thermometer I put out there, it says about 43 degrees in the garage and 12 degrees outside. Looks like it will be a little warmer latter in the week, almost 40 degrees. We will what happens. Thanks for your help!!

[thomasjmdavis]

I would wait. Even many (most?) solvent based spray paints and such will tell you not to use below 50 F. Viscosity of oil and many other carriers and solvents change with temperature  In the old days, this is why we changed our oil to 10w for the winter (lower viscosity) and 40w in the summer. Until someone markets multi-viscosity model paints, I stick with 50+ for rough work with spray cans, and want about 65+ for anything like water-borne acrylics on a model.

Although this doesn't apply to your garage, which seems to have plenty of exposure to the outdoors, in the winter, indoor humidity in the northern part of the US (and Canada and other places north of the northern part of the US) can be very low, and this will also impact paint.  In very low humidity, water-borne acrylics may be dry dust by the time they hit the model, and solvent paints may leave a fog or "crystals" on the surface.

And don't feel bad about your garage.  Mine is currently 15 degrees, same temp as the outdoors. Of course, that means the humidity is the same in the garage as outside, which is around 60%. One of the benefits of country life in a 100 year old farmhouse.

[Scott1984]

Thanks Tom!! I remember when i was doing model car building. I would need to warm the paint up in warm water when it was cooler outside. I have decided to wait a bit. It's hard when you want to get some stuff done and can't do it right away. Also it is not fun freezing in the garage either. After hearing the temp in your garage, I feel like mine temp is good to go. Thanks for the help!! Stay Warm!!

[robert3985]

It might be time to invest in a portable ventilated spray booth.

There are quite a few of 'em out there, all under $100...just crack your window and put the vent in it...turn it on and spray.

Here's an example I found after a very quick Google search....  https://www.amazon.com/Hotorda-Portable-Airbrush-Replaceable-Extension/dp/B08QZFHVJR/ref=asc_df_B08QZFHVJR/?tag=hyprod-20&linkCode=df0&hvadid=663203425629&hvpos=&hvnetw=g&hvrand=3799797834197336681&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9021712&hvtargid=pla-1166899836862&mcid=8fddae0b639937df8b46b37975109e24&th=1

After you're done, just disassemble and fold it up...ready for use another day...

Cheerio!
Bob Gilmore

[ednadolski]

It might be time to invest in a portable ventilated spray booth.

Hmmm... are these really all that good wrt ventilation?

Ed

[muktown128]

OK, I'll add my thoughts as a chemist/formulator of coatings for a large paint manufacturer.

Storage of paints:
Water-based paints can freeze at low temperatures.  Not all water-based paints are freeze-thaw stable, which means that if they freeze, they are no good after they thaw out.  If your water-based paint freezes and you want to know if it is still ok, then check for gels, clumps, chunks, seeds, or kickout.  Stir the paint and if you see anything like this on the stir stick, then you may have an issue.  You can also check color, gloss, and dry time to see if it has changed.

Solvent-based paints shouldn't freeze at low temperatures, but they may phase separate.  Warm the paint back to room temperature and mix well before using.

Application of paints:
Colder temperatures will slow down dry times since it will take longer for water or solvent to evaporate.  It can also ******** cure of alkyds or enamels since the rate of cure is influenced by temperature.

Also, the viscosity of many coatings will increase as temperature decreases.  There can be a pretty large increase in viscosity as temperatures get below 60 F. Colder temperatures may require more reduction to achieve the same viscosity for application.  Adding more solvent or water will dilute the paint, reducing hiding at the same wet film thickness, which means more paint will need to be applied to achieve hiding or coverage.  However, this may not be much of an issue for coatings already reduced for spray application. 

For industrial coatings, it is not recommended to apply at temperatures below 50 F.

Regards,
Scott

[Scott1984]

It might be time to invest in a portable ventilated spray booth.

There are quite a few of 'em out there, all under $100...just crack your window and put the vent in it...turn it on and spray.

Here's an example I found after a very quick Google search....  https://www.amazon.com/Hotorda-Portable-Airbrush-Replaceable-Extension/dp/B08QZFHVJR/ref=asc_df_B08QZFHVJR/?tag=hyprod-20&linkCode=df0&hvadid=663203425629&hvpos=&hvnetw=g&hvrand=3799797834197336681&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9021712&hvtargid=pla-1166899836862&mcid=8fddae0b639937df8b46b37975109e24&th=1

After you're done, just disassemble and fold it up...ready for use another day...

Cheerio!
Bob Gilmore

Thanks Bob for the info on that. Unfortunately I do not have a space in our home for any hobby stuff. That is why it is all in the garage. I would like to have a both but in this case it would not work for me. Thanks!!

[Scott1984]

OK, I'll add my thoughts as a chemist/formulator of coatings for a large paint manufacturer.

Storage of paints:
Water-based paints can freeze at low temperatures.  Not all water-based paints are freeze-thaw stable, which means that if they freeze, they are no good after they thaw out.  If your water-based paint freezes and you want to know if it is still ok, then check for gels, clumps, chunks, seeds, or kickout.  Stir the paint and if you see anything like this on the stir stick, then you may have an issue.  You can also check color, gloss, and dry time to see if it has changed.

Solvent-based paints shouldn't freeze at low temperatures, but they may phase separate.  Warm the paint back to room temperature and mix well before using.

Application of paints:
Colder temperatures will slow down dry times since it will take longer for water or solvent to evaporate.  It can also ******** cure of alkyds or enamels since the rate of cure is influenced by temperature.

Also, the viscosity of many coatings will increase as temperature decreases.  There can be a pretty large increase in viscosity as temperatures get below 60 F. Colder temperatures may require more reduction to achieve the same viscosity for application.  Adding more solvent or water will dilute the paint, reducing hiding at the same wet film thickness, which means more paint will need to be applied to achieve hiding or coverage.  However, this may not be much of an issue for coatings already reduced for spray application. 

For industrial coatings, it is not recommended to apply at temperatures below 50 F.

Regards,
Scott

Thanks for the info on paint chemistry. Fortunately my garage does not freeze. Today the temp outside was 12 degrees and the garage was 43. So we should be good on paint freeze. I only have acrylic paint, so worries about other types. I am going to wait until it warms up a little in a few days. Thanks again!!

[robert3985]

Hmmm... are these really all that good wrt ventilation?

Ed

@ednadolski Ed, I'm sure that some are better than others as far as ventilation CFM is concerned.  But, for N-scale models using an airbrush at 20psi or less, even fairly inexpensive ones should allow for nearly fume-less painting near your most handy open-able window.

The nice thing about a lot of 'em is that they're portable, meaning they can be folded up when not in use and put away...which is great for apartment dwellers, or people who don't have room for a permanent booth inside their homes.

Since I've had a separate workshop for building my models for decades, I've always made sure that I had a window and the space for my spray booth, which I built out of 1/4" plywood with a blower I bought from Graingers.  It forms the center of my paint operations with a furnace filter inside to catch particulates, a couple of airbrush holders, hooks to hold the clamps I use for holding small parts I'm painting and hanging them to dry, a 120V outlet for my hair dryer, and a fairly powerful LED light source that allows me to change the light's color temperature.  It's mounted on its own cabinet where I have both storage and access to my airbrushes, cups, bottles and storage underneath for various solvents, cleaners and my ultrasonic cleaner.  It isn't pretty, but it does the job well.  Maybe I'll get around to painting it one day when the mood strikes me!

Cheerio!
Bob Gilmore

[wm3798]

I'm a simple man with simple answers.
I also share the same problem, as I don't have an indoor workshop where I can set up a paint booth.

Since winter months are typically slow for business, and time flows a little more freely, modeling projects are always coming up on the "to do" list.

Here's my simple solution.
First, I pretty much rely on rattle cans to paint things like concrete abutments, red bricks, black roofs, and of course, Penn Central Diesels...
Store all of your paints and equipment inside the warm place.  When you have everything masked up, step out to the garage, and fire away.
If the surface of the model is warm, the paint is warm, and the interaction with the cold is brief, there's almost never a problem.  At least with solvent based paint shot from a can.
In some circumstances, I've kept a pan of warm water handy to bring a can of paint up to temperature if it's been left out in the cold.  This seems to help the flow, even when it's not so cold out.

More intricate work with acrylic paints might require more attention, but for structures and basic stuff, this method is pretty fool proof.

I have used alcohol, maybe cheap vodka for instance, to thin acrylic paints for the air brush.  This might help in cold conditions, since the thinner will have a lower freezing threshold, and also will evaporate and dry faster.  Plus the vapors make painting while you're freezing your kiester off much more fun!

Lee

[ATSF_Ron]

This is all good stuff! I’ve also decided to delay a couple painting projects as well due to cold/wet weather here for the next several days.  While my garage is insulated, it still can drop to where paint application can be iffy.  Lucky for me, it faces west and warms up nicely when the sun is out.  I have never shot paint below 60 degrees, and this thread has convinced me to wait for warmer times.  I do have a portable heater that’s quite effective, but I’d definitely turn it off if shooting any flammable paint in the same space! 😳