DansYellow66

Planning to paint my Cobra replica with single stage PPG black next week and the long range forecast is now showing lower high temperatures than a few days ago - in the mid to high 50s. I have a spray booth enclosure built in a friends unheated warehouse. We can heat it with a salamander heater but that will introduce some humidity in the air - although now the forecast is at least showing the rain moving out before I planned to start painting on Wed. I've read that black can be affected by humidity. I also planned to have some small halagon lamps on the floor outside the booth to add floor level illumination and that might add a little greenhouse effect. There are 6 double tube flxtures in the booth that might add a little heat from the ballasts. But I have a pretty good exhaust fan and it's going to pull fairly frequent air changes through the booth.

So what is a real temperature minimum threshold I need to pay attention to? I was shooting for a minimum of 65 deg in the booth but now I'm not sure if I can meet that without running that salamander heater a lot. I've heard of 60 as a cut off where urethane no longer chemically cures.

Any tips for safely inducing heat in some form into a ventilated PVC/visqueen booth?

Right now all I know is set it up and monitor the temperatures and see what it stabilizes at in the late morning. It will be tough to find warmer days from now until spring.

CF6873

I have painted many cars using a kerosene torpedo as the heat source.

The most important safety issue is to make sure that no paint fumes

reach the heater. I always placed it outside of the paint room on the

intake side so the that the fan would draw the warm air into the paint

room. I still see many shops that use similar heat sources to warm their

spray booths in cold weather.

The toughest thing about painting in cold weather is that the

paint will want to run and sag much faster. Also flash time will be much

longer increasing the probability of getting dirt and trash in the paint.


Good Luck

Craig

DansYellow66

That gives me some hope. I will have a pretty tight painting enclosure so maybe that will help with the trash and slow set times.

Spraygun

Your car should be at least 60 degrees, having the air temp 60 in your booth doesn't mean the body panels are. If I put a car in the booth (downdraft with heat) if can take up to several hours for the panels to reach the temp of the air in the booth. Having sprayed in cold conditions in poor quality booths I suggest getting an infared thermometer, Horrible frieght has low priced models. In a garage that reads 70 on a wall therm. the rockers can be much colder depending on the conditions.
This goes for ALL isocynate products. If you sprayed 2K primer at 50 and a week later sanded it and sprayed topcoat at 60 you run a risk of shinkage, loss of gloss when you pull the car out into the sun and it heats up. It was explained to me that the isocynate cross linking process slows down as temp drops, below 60 is risky.
Paint companies make extra fast hardners, Glasurit use to make a polar hardner, will the topcoat cure? yes. Would you want to use it to spray your corvette? Don't think so.
Another thing to consider is that you will need air movement through your booth while spraying. If you draw cold outside air over your 70 degree car while your spraying it'll be difficult to achieve a uniform glossy finish.

DansYellow66

I'll take my infrared thermometer over and see what it says. It was about 67 F in there today and I shot some 2K sealer this afternoon - but that's another story.

Thanks

I'll move my thermometer in the booth down closer to the floor also.

leadfoot4

This goes back a long time, but I painted a couple of cars in early spring or early fall, when the outside tepms were in the high 50s-low 60s, using acrylic lacquer, and heated the shop with a kerosene salamander.

I noticed the salamander was leaving an oily film on the car. I had to turn it on, warm the shop for a couple of hours, then shut it down, let the air settle, then go over the body panels with degreaser RIGHT BEFORE shooting the paint.

Just something to keep an eye out for....

porchdog

you can warm the body with old electric blankets over nite . but anything below 65 and you are risking a multitude of problems. it's ok to do repairs and such at lower temps but an overall is a different story.

markids77

I shot the 77 this weekend at 65 ambient after a 40something night. Started shooting at about 1 o'clock and the first coat (PPG Omni MAE acrylic SS and fast reducer) went on pebbly but flowed out OK except for a dry edge from panel to panel. I shot the second coat using 1/2 fast and 1/2 slow reducer to try and keep a wet edge, but ambient had dropped to about 63 and the paint refused to flow at all causing massive peel . Increased air/reduced liquid helped some but I would not recommend trying this at home. It seems to be wet sanding/polishing out OK but I had gotten much better results on some panels shot earlier with the temps in the low 70's. Unless you can be certain your car is at 70 or so, and can keep the booth there for at least 24 hours as well I would recommend you wait for more favorable weather.