Spray painting in cold temperatures?

[Mike Chantler]

Help! I'm planning to use rattle cans to paint a 60" model red in my garage. Tomorrow it'll be 8 degrees C if I am lucky.

I've got Montana black cans and wing and fuselage done in yellow Hycote deep fill primer.

 

What goes wrong if the temperature is too low?

 

Should I heat the cans up first in hot water first?

I've also got a 3 bar wall heater that I could use to put radiant  heat onto the model - would that help?

 

Also - do I need a grey primer or can I just go straight to colour? i get the feeling that the Montana cans have good covering power so am tempted to miss out the grey.

 

Any help / tales of previous experience appreciated!! Or pointers to relevant threads.

 

Thanks.

 

Mike 

 

 

 

 

[Brian Cooper]

Spraying in low temperatures will create a dull "bloom" to the finish. 

Heating the spray cans and also heating the item to be sprayed will help, but try to get the workshop warmed up.  This will dry the air too. 

 

Good luck.

 

[Martin Harris - Moderator]

This was my solution to spraying in cold weather - the heater was turned off for safety just before spraying!  I'd make the tent bigger next time as it was a little cramped but it worked well and kept the spraying area dust free as well.

 

     

 

 

 

 

 

[Dale Bradly]

Your paint, your surface and the air in between all need to be above a minimum temp which is probably printed on the can, often 15-20°C. Below this, the paint will not adhere properly to your surface. It may go on, but will fall off at the first sign of hangar rash or otherwise be fragile. So do whatever you have to do to get all the variables above minimum.

I recommend a primer of some form, but at least have a single colour base coat,  whether that be primer, undercoat or a neutral grey or similar, as the top coats will reflect what's underneath, especially whites, reds and yellows.

Note that spray bombs with "good covering power" means they have a lot of filler to achieve this, this makes for a heavy paint. May or may not matter on your project.

[Ron Gray]

I’ve used the Montana paints quite a lot and even though they have excellent coverage I’ve always used a primer / undercoat well rubbed down. If you want the red topcoat to really’ pop’ use a light undercoat. As other have said it is important  get the temps up before spraying, heating the rattle can up will help the paint flow through the spray cap.

[leccyflyer]

I was thinking of getting one of these to make a wee spray booth in the garage. It ought to be quite easy to warm up, with an oil filled radiator inside, would keep dust off the sprayed airframe and keep overspray off everything else in the garage. The only difficult I would envisage would be suffocation, but I'd be wearing a respirator and I only really use water-based paints these days. Am I missing something?

https://www.wilko.com/en-uk/wilko-walk-in-pe-greenhouse-with-cover-shelf-staging-h190-x-w120-x-d190cm/p/0260896

[Paul De Tourtoulon]

Like Martin 'but' out in the sun or in GB  with none of that luxury the garage with a small electric heater, but then I only use 2 part polyurethane paint, and always a proper primer.

 

This is all I get Leccy,,,,

Edited February 20, 2022 by Paul De Tourtoulon
Leccy

[Denis Watkins]

Wilko

 

Edited February 20, 2022 by Denis Watkins

[leccyflyer]

Worked for me - now ordered @ 20% off, delivery Tuesday - what a bargain. I'll let you know how it works.

 

A search at Wilko's online shop for plastic walk-in greenhouse should work.

[Nigel Dell]

S

2 hours ago, leccyflyer said:

I was thinking of getting one of these to make a wee spray booth in the garage. It ought to be quite easy to warm up, with an oil filled radiator inside, would keep dust off the sprayed airframe and keep overspray off everything else in the garage. The only difficult I would envisage would be suffocation, but I'd be wearing a respirator and I only really use water-based paints these days. Am I missing something?

https://www.wilko.com/en-uk/wilko-walk-in-pe-greenhouse-with-cover-shelf-staging-h190-x-w120-x-d190cm/p/0260896

That’s a great idea Leccy added bonus you are not painting everything around you too??

[leccyflyer]

That was my concern Nigel - I store my models there and was worried about overspray.

[Paul De Tourtoulon]

That looks nice I will ask my wife to get it for her planting her flower seeds,,,?,,,

[Mike Chantler]

Thanks for all the info guys ??. Have definitely been persuaded to test out first - never thought of the paint coming off in hanger rash due to cold!

 

Had a look at the spec:

OPTIMAL PROCESSING CONDITIONS:    

 - Temperature 10° - 25°Celcius

- Surface temperature 5° - 40°Celcius

- Air humidity max. 60%

The Montana Black have 'Nitro Combi Base'  - I seem to remember that other spray paints I have used in the past need higher temperatures.

Ordered these as saw post from Ron previously.

I have never used before, I'm just a bit worried that it has cellulose in the base and may eat my primer ?

 

[Mike Chantler]

3 hours ago, leccyflyer said:

I was thinking of getting one of these to make a wee spray booth in the garage. It ought to be quite easy to warm up, with an oil filled radiator inside, would keep dust off the sprayed airframe and keep overspray off everything else in the garage. The only difficult I would envisage would be suffocation, but I'd be wearing a respirator and I only really use water-based paints these days. Am I missing something?

https://www.wilko.com/en-uk/wilko-walk-in-pe-greenhouse-with-cover-shelf-staging-h190-x-w120-x-d190cm/p/0260896

 

That looks really good - may well order. Hmmm.... beloved my nick it when it arrives for her seedlings!

[Mike Chantler]

Model is quite light at the moment - so will be interested to see how much weight it will add.

[Ron Gray]

30 minutes ago, Mike Chantler said:

I have never used before, I'm just a bit worried that it has cellulose in the base and may eat my prime

I've not had a problem with the topcoat attacking the primer, and I use the cheapest ones I can find on Amazon! Make sure that the primer is cured (in the summer I've only had to leave it for a couple of hours, but I would leave it for a couple of days in this weather, unless in a heated store!) well rubbed down and dusted off and apply only thin coats of topcoat letting each one 'go off' before applying the next.

 

The Montana sprays are designed for graffiti work and as such work in outdoor environments!

[Kim Taylor]

Just re-iterating all of the above advice really, but to add my own 2p worth - the bloom is caused by water in the air, so warm air = dry(er) air.

Wrt your topcoat vs undercoat, the best tip I would give is to give an overall 'drop' or mist coat 1st, and allow to tack off before adding more light coats. Going on 'wet' with your 1st colour coat is when you'd get a reaction (if you were going to).

If you make up a tent or similar, as already said, don't forget ventilation - unless you're using an air fed respirator (rather than a canister mask, or similar) you can still suffocate if there's enough spray mist in the air. For anyone using 2K please remember the mist is also highly toxic (unless you're using isocyanate free products, which tbh is unlikely as they're a bit rare / expensive). Ventilate freely (i.e. no enclosure) and use a good canister mask with the appropriate filters, or use an air fed mask. Guess how I know!! ?

Kim

[Mike Chantler]

Thanks Ron.

Have you ever used their 'gold' cans for smaller areas?

 

@Kim, thanks for the safety info. A good reminder. Ideally I'd like to spray outside, I'll see how weather goes in the next few weeks. At the moment it's definitely damp!

[leccyflyer]

53 minutes ago, Kim Taylor said:

Just re-iterating all of the above advice really, but to add my own 2p worth - the bloom is caused by water in the air, so warm air = dry(er) air.

Wrt your topcoat vs undercoat, the best tip I would give is to give an overall 'drop' or mist coat 1st, and allow to tack off before adding more light coats. Going on 'wet' with your 1st colour coat is when you'd get a reaction (if you were going to).

If you make up a tent or similar, as already said, don't forget ventilation - unless you're using an air fed respirator (rather than a canister mask, or similar) you can still suffocate if there's enough spray mist in the air. For anyone using 2K please remember the mist is also highly toxic (unless you're using isocyanate free products, which tbh is unlikely as they're a bit rare / expensive). Ventilate freely (i.e. no enclosure) and use a good canister mask with the appropriate filters, or use an air fed mask. Guess how I know!! ?

Kim

I think that is very sound advice, especially for the toxic and solvent based sprays. For spraying water based paints, providing ventilation is going to remove one of the requirements for me, of preventing the spread of overspray within the garage. With a canister mask would you say that it would be okay to stay in there for a few minutes, or would you still  need to have an air fed system then?

[PatMc]

2 hours ago, Kim Taylor said:

Just re-iterating all of the above advice really, but to add my own 2p worth - the bloom is caused by water in the air, so warm air = dry(er) air.

 

I agree that water in the air causes the bloom but the driest place in the planet is in an Antartic desert. OTOH the highest humidity is possible in the warmest air which is why the most humid places are near the equator.

I think that bloom is most likely when the air is close to it's dew point regardless of the ambient temperature - i.e. when humidity is close to 100% & the air is cooling. 

Edited February 20, 2022 by PatMc

[Kim Taylor]

11 minutes ago, leccyflyer said:

I think that is very sound advice, especially for the toxic and solvent based sprays. For spraying water based paints, providing ventilation is going to remove one of the requirements for me, of preventing the spread of overspray within the garage. With a canister mask would you say that it would be okay to stay in there for a few minutes, or would you still  need to have an air fed system then?

Just bear in mind that as the mist builds up, the air available to breathe reduces proportionally. Your own tolerance / discomfort levels may vary, depending on whether you have (for instance) athsma or something similar. 

Personally, I'd be comfortable using a cannister mask for 'normal' solvent based and water based paints within a tent but with some form of ventilation (say a fan at one end blowing through to an exit) but being aware of the overall level of spray mist in the air. Common sense will see you safe.

Kim

ps sorry for late reply, been out walking the dog!!

[Kim Taylor]

36 minutes ago, PatMc said:

I agree that water in the air causes the bloom but the driest place in the planet is in an Antartic desert. OTOH the highest humidity is possible in the warmest air which is why the most humid places are near the equator.

I think that bloom is most likely when the air is close to it's dew point regardless of the ambient temperature - i.e. when humidity is close to 100% & the air is cooling. 

Yes, you are quite right - I was just referring to the particular circumstances being discussed i.e. a cold day in a UK winter, sorry to have implied otherwise.

Kim

[Engine Doctor]

When spraying  cellulose or acrylic in cool but high humidity to avoid blooming anti bloom thinners are best used. Unfortunately using aerosols makes this impossible. Anti bloom thinners are a high quality thinners with retarder to slow the drying. Also used in good warm conditions to get a good flow and gloss on cellulose paint if ordinary retarder thinners are not available. 

Many of the aerosols  now use all sorts of paint concoctions and knowing what's best or what to use if it blooms is a bit of a lottery. Unfortunately just applying another coat also adds a surprising amount of weight! I recently sprayed a repaired cowling with what was supposed to be a white cellulose type paint that I hadn't used before. I then applied a thin coat of two pack clear as I have done hundreds of times before with different brands and it all pickled .

Re the colour of primer. Test first as the primer colour can really affect the finished colour. Hi - build primers like the yellow Tetrosyl spray putty should be sanded back only allowing thicker layers to fill minor imperfections as it's very heavy. Then a thin coat of appropriate colour primer applied.

If spraying equipment is available then a thin coat of thinners often allows the bloom to evaporate out and the paint to dry to a normal finish. 

Enamel paint is a tottaly different animal and requires a different application technique. It usually covers much better than cellulose or acrylic , is slower drying , never known it to bloom but will run if applied too wet and is heavier by comparison so avoid heavy build up.

If you spray regularly then dump the rattle cans and invest in a small compressor and spray gun and make sure to add a decent appropriate mask or respirator to the shopping list.

 

Please note all of Kim Taylors advice above as paint can be dangerous or damaging to health especially when spraying. You might be OK for years but it will catch up with you if your not careful.

 

Edited February 22, 2022 by Engine Doctor

[Andy Stephenson]

Spray gun

Pros

• Mix any colour you want
• Ability to adjust paint consistency
• Ability to adjust spray pattern and density

Cons

• Cleaning the gun after every session or colour change
• Cost of the gun and compressor
• Requires the use of a great deal of solvent
• Some paints not available in small amounts

Spray cans

Pros

• No cleaning apart from clearing the nozzle
• No mixing or messing around with paint spillage
• Purchasable in relatively small amounts

Cons

• Limited range of colours available without the extra expense of having a custom colour mixed

I use both gun and aerosol but if I can find the colour I need in aerosol that's what I will use.

 

I found this at Halfords recently, it's called leveller, I wasn't sure what it was until I read the label. It's effectively just thinners in a spray can. It's primary function is to level out the orange-peel effect and dusty overspray some sprays leave behind but it would also be useful for removing any bloom when the conditions permit.