Working on my OT LBC, which I consider my classroom to improve my skills, and I've run into a painting problem. I've lost my temp time to spray as the days are cooler now. Temps around low to mid 50s during the day and of course cooler at night. I didn't get to the body tub and therefore can't reassemble all the fenders, doors, etc. I will be installing a radiant heating system. One will take a little time to sort out and it's the one that has an enclosed combustion chamber, the other is open. So is there any way I could paint with the unit that is not enclosed? My ceiling is about ten feet. Floor area is around 900square feet. How long does it take for urethane fumes to be disapate before everything would go boom? I was hoping I might be able to warm up the space overnight, turn off the heater, paint, wait awhile and then turn the heater back on. I'd leave the garage door open a few inches to allow cross flow ventilation. Pipe dream or doable?
I wouldn’t be comfortable doing any combustible fumes type work without a closed combustion system like my radiant tube heater has. It has a fresh air intake and no standing pilot so nothing goes boom. It’s the only safe way to go.
Not saying it’s the smartest way to go but in my younger years I painted a lot in a shop with a wood stove.... Sent from my iPhone using H.A.M.B.
Well I guess I'll wait a little longer and reconfigure my storage a bit. One of my radiant heaters is enclosed. Right now I have a lot of 1/4 sawn fir flooring right in front of where the heater will go. That wood is in perfect shape and must be 85 years old. Maybe I should build a woodie! LOL
We painted airplane parts in the winter with a wood stove with waterborne epoxy.. We built a spray booth in the shop with a plywood duct vent out through a plywood plug in the back door opening. Before we built a booth similar to the one Blue One built we would heat the shop up to about 85 degrees and let the heat soak in to the shop. We opened the garage door to clear the mist so as the cold air rushes in an the warm air goes out fast with a quick exchange of the air. Then we closed the garage door and the heat would recover quick and that was at temperatures as cold as -25C. The real hazard is if spraying any paint with an isocyanate based in a closed space without a constant air change is a toxic environment that can precipitate into a severe reaction. Even with a mild reaction that reaction may get worse with each exposure. Isocyanate is extremely toxic. Epoxy is okay as its hardener is a non-isocyanate. With the booth, we would crack a door so that there was fresh air coming into the shop to replace the air expelled when the fan ran then closed the door & shut the fan off once the air was clear in the booth. The shop never got down to 72F anytime during the process. Our blower was an old furnace fan in a plywood box with furnace filters on 3 sides and the top so we did not send out a coloured exhaust. Our booth was near the back door so our duct was made with sheathing plywood. I think with an inexpensive poly booth under negative pressure that it would be reasonably safe with just about any heat source as there are no fumes released into the shop space. If the heat source uses shop air for combustion air then definitely want to crack a door to prevent a vacuum with a good sized exhaust fan. Pulling a vacuum in the shop could cause a back draft making the heater exhaust into the shop with air coming down the chimney. Friends of ours had that happen in their house at Christmas with their wood burning fireplace with no fresh air inlet running wide open. It was in the -30's and when the gas furnace kicked in people started to feel woozy and sick. Cold air was being drawn down the furnace flue and when it kicked in it could then it could not reverse the air flow so it was exhausting in the house. They were glad they were not sleeping when that occurred or it could have been really bad.
Agree with the exhaust fan even though using my hvlp gun doesn't give off very much overspray at all.
I painted several with a kerosene forced air heater. Get the car as warm as possible, shut off the heater and spray. then crank the heat back up after spraying. the surface temp is important. Never an issue. But I might just be lucky.
I'm with Anthony. I've painted 100's of cars like that. Heat that shop up to around 90 degrees and let the car soak up the heat. And currently i have a pot belly stove in my shop. Have for probably 10 years? I've heard stories of guys using their bic lighter as a flashlight to check paint coverage inside of a trunk and it blew up, but I guess I'm lucky it's all about lower explosive limits and upper limits. Just like your carburetor, ya gotta have that perfect oxygen level for it to happen. But I still lay the back of my hand on the car, it's the temperature of the metal that I'm worried about. And after the overspray clears, i warm the joint back up. Urethane likes 60 degrees f. But I'm no scientist lmao.
This thread brings to mind a situation back in the early '60s. Good friend and co-worker had built a really nice '34 Ford coupe and had primed it in his garage/shop and I helped him with the block sanding and prep for paint. The man doing the painting (black lacquer) had been in the body and paint business just about forever. Told us a story about working in the old Ponce De Leon Ave Ford plant in ATL where he did the hand pin striping on one side of the '34 Fords coming down the line and another man with a bit more seniority painted stripes on the other side, getting .$.60 hr. while he got $.50! They were the 2 senior men in the paint shop! We got the '34 into the room where he painted cars, partly basement, partly ground level. It was Winter and cold, with an open radiant natural gas heater burning brightly. As Mr. Akin went about mixing his lacquer and thinner, I asked him if he wasn't worried about the open flame heater, as he was ready to start spraying and the heater was still burning brightly. He grinned as he spoke and said "Son, if the fire's already there when you start spraying it will just burn instead of blowing like it would if you started a fire or a spark after you had already gotten an explosive mixture in the spray booth." With that, he turned and grinning, sprayed the lacquer directly into the open flamed heater! The flame flashed briefly and the heater resumed burning normally! BTW the '34 earned a several page spread in HRM.
Now that is an interesting take on this. It seems to make sense from a science perspective if the fumes start off at the same level as the flame. However if the fumes were to migrate to the same level I'm thinking that's when things could go boom. I may run this idea by a neighbour who is Fire Dept. Captain...
When it comes to radiant heat if the heater is not centred in the area will that create warmer areas closer to the heat source versus areas further away? Will the heat even out as the area warms up overall? Helping to decide on radiant heater placement...
My ceiling is only 8’ and because of that it limits the location choice of the heater. Mine is in the back of the garage in the top corner angled down at 45 degrees. The radiant heat warms up everything in the garage and it does even out. When the heater is on you can sense that it’s a little warmer on that end. Because of the nature of heat rising most shops with higher ceilings will have one or two ceiling fans to push some of the warm air that builds up down. Even though radiant heat warms up every thing without forced air movement that doesn’t mean that the top section won’t be warmer with a higher ceiling.
The type of radiant heater I'm typing about sometimes just had a stamped metal frame and some of the fancier had a decorative art-deco style body molded from ceramic material. The so called "radiants" rested on a frame work directly above the burner bar and were heated by the open flames the radiants were ceramic and would glow brightly from the heat, thus radiating the heat out into the room. But I agree with Blue One, the heat is more up close to the heater, especially till things warm up a bit.
I have done the same method. I am always just a tad nervous when I turn that heat back on, but haven't barbecued myself yet! I have a wood stove on the side of the shop that I intake air from and then I have an exhaust out the floor in the paint booth. I still heat the booth itself with the forced air heater before and after spraying.
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