Epoxy & Poly Primer Curing

B

BradNes1

Hi guys, I've been doing some spraying this week and want your opinion on how long I need to keep my garage up to temp. See below for my process.

Monday night - sprayed 2 coats of epoxy with 1 hr between coats, I let epoxy induce for 60 minutes before spraying.
Wednesday night - Sprayed 2-3 coats of poly primer with approximately 20 minutes between coats.

I have been keeping the metal temps at a minimum of 65 degrees (measured at the rocker panels) this whole time but it's currently negative 4 degrees with about a 25 below windchill and it's costing me a fortune! How long do I need to keep the heat on before I can shut it off and not have any curing issues with the epoxy or poly primer?
 
I've read a minimum of 24 hours @ above 65 for epoxy, minimum 24 with 48 recommended prior to poly. I'd say you are doing very well! I'm assuming your poly is activated and will probably be cured fully by tomorrow but maybe someone with more experience can jump in and confirm.
 
Someone had mentioned using a heating blanket to keep heat on a panel while curing. May not be so good for a whole car.

Mike
 
In our shop, the heat runs 24/7 when there are coatings curing. Sometimes we turn it down a bit (60°F) if they are fairly well cured, but putting fresh coatings into a deep freeze to save a buck is penny wise and pound foolish. Large temperature swings are bad for everything else in the shop too, paints, putties, adhesives, you name it. I would just say that if the work space can't be consistently and continuously climate controlled, it's best not to do paint and body projects in the winter at all.
 
I mentioned before the possibility of using a heat blanket for some extra night time heat on a partly cured part done in good daytime temps, but that was mainly southern area advice that wasn't actually tried yet that I personally know of. It's still a hmmmm?? type of thought.

Crashtech's advice is nothing short of fully true from experience. Besides the slowing of product drying, every material known to man expands & contracts a certain amount in temperature changes. Extreme temp changes particularly to freshly done work will makes issues like shadowing at welds, joints, & more bodyworked areas more likely to happen.

Minimum safe temperature really is a slower drying temp, I'd hate to see it drop much under that for a couple of days & at least keep some heat in there for a few more days minimum if it's that d-word cold outside. Your topcoat paints aren't near as sensitive, but I'd hate to see them drop below freezing for at least several days also.
If you could possibly shrink down the work space after spraying to heat less air (hanging heavy tarps, etc), this could be an option.
Also may not be a bad idea to wait & do any color sanding after the paint finally gets some decent weather sun curing.
 
One thing I do to help circulate the heat so it doesn't stay at the ceiling between heater cycles is use a small CFM recirculating fan that's mounted on the ceiling and aimed on a downward angle. Nothing large, just enough to keep a gentle, small circulation.

Mike
 
Sorry guys, my original post was worded a little poorly. I keep my garage heated all winter long but prefer to keep it around 50 degrees or so. I'm not looking to completely shut off the heat and freeze the paint. The issue is in order to keep the bottom of the rockers (the coldest part) at 65 degrees I need to keep my whole garage at about 80 since there is no insulation under my concrete slab. I can keep the heat up if I have to but I didn't want to keep it so warm if it's not necessary. The poly primer seems to have set up fine last night and I am keeping the metal temps around 50 degrees as of this evening (72 hrs after first spraying epoxy). I'm assuming this will be fine for the epoxy since I read Barry mention previously the epoxy needs to be kept up to temp for at least 24 hrs? Out of curiosity do most shops bake the cars to get around this issue or do they just not use epoxy for this very reason? No one I know has ever had to wait a week to get their car back from the body shops because the primer is still curing and the shop doesn't want to send it out in the cold weather.
 
BradNes1 said:
Sorry guys, my original post was worded a little poorly. I keep my garage heated all winter long but prefer to keep it around 50 degrees or so. I'm not looking to completely shut off the heat and freeze the paint. The issue is in order to keep the bottom of the rockers (the coldest part) at 65 degrees I need to keep my whole garage at about 80 since there is no insulation under my concrete slab. I can keep the heat up if I have to but I didn't want to keep it so warm if it's not necessary. The poly primer seems to have set up fine last night and I am keeping the metal temps around 50 degrees as of this evening (72 hrs after first spraying epoxy). I'm assuming this will be fine for the epoxy since I read Barry mention previously the epoxy needs to be kept up to temp for at least 24 hrs? Out of curiosity do most shops bake the cars to get around this issue or do they just not use epoxy for this very reason? No one I know has ever had to wait a week to get their car back from the body shops because the primer is still curing and the shop doesn't want to send it out in the cold weather.
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Most production shops do not use epoxy primer ......hell a lot of them don't even know what it is
 
Wonder if parking over a few pieces of plywood could help, wood is an insulator. Could possibly even have single thickness sheets of urethane foil backed insulation under plywood & drive on it.

Poly primer isn't as sensitive as epoxy, you're probably good.

And yea, most production shops don't use anything that will slow them down in the name of quality
 
you should look into some infrared light fixtures and just point them, (you might want to sit down) at the concrete. We bake powder at 400 degrees most of the day, that concrete under the oven can hold the temperature for hours. I either point the light at the booth or at the floor if I want to keep the temp up. Its also -3 here today, we sprayed epoxy yesterday and the booth is 65 with just the lights on.
 
heating the concrete is a great idea, especially if you don't keep your shop warm 24-7, if I ever build another shop it will definitely have radiant heat...
 
if you ever build another shop build it where negative temps are against the law .......

concrete keeps your temps up. it was 20 degrees here this morning. shop temp was 47 with no heat .
 
hpete said:
heating the concrete is a great idea, especially if you don't keep your shop warm 24-7, if I ever build another shop it will definitely have radiant heat...
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I have hydronic heat in my shop and yes, it is the greatest thing since sliced bread.
 
Radiant floor is nice but does have it's draw backs like if you decide to anchor something to the floor you had better hope you don't hit one of those water lines. The heat is nice for sure but I'm leaning towards tubular IR it heats objects including the floor not to mention the metal of a car warmer then floor heat ever could. It too has draw backs like a car lift putting the roof too close to the tube but that can be easily rearranged if needed. If you already have a garage with finished floor tube IR is a no brainer if you have the ceiling height.

You can also get those red IR heat bulbs (flood light) on a fixture and let it glow on the surface while you are not in the shop to keep the surface warm.
 
DATEC said:
Radiant floor is nice but does have it's draw backs like if you decide to anchor something to the floor you had better hope you don't hit one of those water lines. The heat is nice for sure but I'm leaning towards tubular IR it heats objects including the floor not to mention the metal of a car warmer then floor heat ever could. It too has draw backs like a car lift putting the roof too close to the tube but that can be easily rearranged if needed. If you already have a garage with finished floor tube IR is a no brainer if you have the ceiling height.

You can also get those red IR heat bulbs (flood light) on a fixture and let it glow on the surface while you are not in the shop to keep the surface warm.
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Very true. Careful planning is in order here.

What is a good source for tubular IR ? I was thinking of adding a little supplemental heat in a sectioned off area.

P.S. Sorry for the hijack.
 
I wouldn't be afraid to get a Reznor off Ebay, they can be had cheep for a good used one, not much to go wrong with them.
 
Greetings, here is what I use, http://brantradiant.com/products/hl2-series/ I did a fair amount of research before I installed the heater.
I would recommend that you look at 2 stage IR tube Heater.
I keep my shop at 50 when not in use and turn it up to 60 - 65 when I'm working. Two stage heater works like this. I turn it up to 65 from 50 and the heater uses the high stage at 200,000 btu kicks in and warms it up to 65 then it switches to the low stage and uses 60,000 to keep it at temp. Most tube heaters are single stage so you only get full blast turned off and on. I love mine and would do it again in a heart beat. It takes about and 1 to 1 1/2 hours to get the shop up to 65 from 50 ( I think) it runs very quite so I set it and forget it, I hear it start but that's about it.
I have 2x6 insulated walls, 2x4 celling insulated, celling is 14 feet high and my shop is 30x60 and no insulation under the slab, my highest bill has been $120 for one month. First time I sprayed SPI epoxy when it was freezing outside I turned the shop up to 70 and laid painters tarps down and shot the primer. Then I opened the doors to clear out the air, allowing frozen air into the shop until I closed the shop up. I was using an IR thermometer to measure the metal temp, it was not affected by my the polar air purge. I started to measure other things just to see what temp they were. Everything in the shop was omitting 70 degrees, floor, lift, cars, walls, everything. It takes very little time to heat the shop when the air is the only thing that is cold. I have worked in shops that have forced air heater that it would take a long time to warm up the shop after opining the door in winter. I can leave mine open for 10 minutes and it still warms very quickly.
Hope this helps.
Greg
 
The current shop I work in has multiple tube IR's so I'm very familiar with their performance. In the new shop I'm going to put together I looked into both ways to heat it and tube IR has my vote. Not to mention it's cheaper to buy and install too.
 
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