Newbie- Epoxy cure question

S

SEOK

Promoted Users
Hi all, new member, and new to SPI and painting in general.
I recently purchased SPI epoxy to use on my project. I don’t have a booth, and work on the car in my garage or driveway panel by panel as time allows. The front clip is done and ready to seal up the work. Again I can only work on it in pieces so I thought sealing it in epoxy would be the way to go until I can get it all ready to paint. Plus the car would be moved around and possibly driven to other shops for convertible top work in the same time frame.
My question is, I notice epoxy requires 24hrs at minimum 65 degrees to cure. We have 80-90 degree weather right now but at night it may drop to about 55. If I don’t have a way to keep it at 65+ for 24hrs straight am I screwed? Or would it be ok and just take a couple days in the sun even with the few hours of early morn temp drop? I’d hate to think I just spent $320 on epoxy that may not work for my situation. What would some other options be? I do have the fenders in epoxy (different brand) that didn’t require that temp/time so I didn’t even think there would be this requirement before purchasing. I’ve heard this product is great and would like to jump on board
Help a guy out with some advice??
Thanks
 
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Does it really get down to 55° inside your garage after an 80° day? Do you have an infrared thermometer? Some people play fast and loose with the temp requirements and get away with it, so the advice you get may vary a little. But it's important to know exactly what you have going on before proceeding. Harbor Freight has inexpensive infrared thermometers if you don't have one.
 
crashtech said:
Does it really get down to 55° inside your garage after an 80° day? Do you have an infrared thermometer? Some people play fast and loose with the temp requirements and get away with it, so the advice you get may vary a little. But it's important to know exactly what you have going on before proceeding. Harbor Freight has inexpensive infrared thermometers if you don't have one.
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It may not get that low, the temp outside says 55 from about 2am- 8am so I have a 6hr window of cooler temps but my garage MAY still stay warm enough. Just didn’t want to chance it without asking first
 
Got a HF infrared thermometer, I’ll watch it tonight and see how the temp is. If all is well I’ll seal the hood first thing in the morning and leave it out in the heat all day
 
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Prime the car early in the day outside, leave it in the sun, and keep the garage door open. Around 4pm put the parts in the garage and shut the door. Unless the wind is howling all night long, and your garage is a sieve, it will not get below 65 inside.
 
RenewAP said:
Prime the car early in the day outside, leave it in the sun, and keep the garage door open. Around 4pm put the parts in the garage and shut the door. Unless the wind is howling all night long, and your garage is a sieve, it will not get below 65 inside.
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Thanks, it’s pretty calm here. I’m gonna bet it stays warm enough. The garage is detached and in direct western sunlight so I’m sure it’s cooking.
 
Interesting. Years ago I got a temperature and humidity gauge that's mounted on the wall of the shop to answer exactly what crash asked. It has a re-settable min and max reading so you can see what happened over night.

I would never paint without that. It just way to useful. I learned that the maximum humidity would be at the lowest temperature of the day which is right before dawn. No question about what temperature it is when mixing or spraying.

They are all over now and for less than $10 I think every paint booth should have one.
Here is an example;
Min-Max Temp and Humidity Gauge
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Wall-mounted thermometers are handy, and a good start. They're all we had for many years. In practical experience, I have found that the air temperature they measure can be very different from surface temperatures on various parts of the vehicle, especially during cold weather. I've seen rocker panels be at 60° while the roof was 70°, of course that's with no floor heat.
 
Ok hood is primed! Temp was good all night, never dropped under 69. woke up and shot it this morning . It laid down good. This pic was taken while wet and It did level out a tad more. But because I had to paint outside I got some debris in it and a few dry streaks (from my lack of experience) while trying to keep a consistent distance/speed reaching over this monster hood. Applied 2 coats 40min apart. I guess I can leave it as is and when the time comes to paint it I will have to scuff anyway,
But I am a bit of a perfectionist and don’t like looking at the hood like this. Could I lightly scuff down the dry spray and knock out some of the debris and shoot one more coat later today or tomorrow to smooth it out? I know it can be recoated within 7days without sanding but would scuffing the surface this soon be an issue?
On a side note, being a novice, I’m extremely happy with how my body work turned out. This hood was bad and it came out nice and straight thank god
Thanks for all the help.
IMG_8636.jpeg
 
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SEOK said:
...Could I lightly scuff down the dry spray and knock out some of the debris and shoot one more coat later today or tomorrow to smooth it out?...
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Yes you can, though you may need to wait more than 24 hours, typically between 24 and 48 hours before the primer can be dry sanded without excessive balling up and clogging of the sandpaper.
 
crashtech said:
Yes you can, though you may need to wait more than 24 hours, typically between 24 and 48 hours before the primer can be dry sanded without excessive balling up and clogging of the sandpaper.
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Ok great! I’ll give it a couple days. What grit would you recommend? I was thinking just a gray scuff pad and lightly go over the junk and dry areas. ?
 
If I am going to sand primer, I rarely miss an opportunity to block it so it is straighter. To do otherwise is piling on material for no good reason, in my opinion. But if you don't want to do all that work, a red pad would be more appropriate than a gray pad. Trash should be sanded out with sandpaper.
 
crashtech said:
If I am going to sand primer, I rarely miss an opportunity to block it so it is straighter. To do otherwise is piling on material for no good reason, in my opinion. But if you don't want to do all that work, a red pad would be more appropriate than a gray pad. Trash should be sanded out with sandpaper.
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Makes perfect sense, I’m not opposed to doing the work and blocking. I’ve already put so much time into it might as well block once more. 320-400?
 
It really depends, but if this is the first primer on something that has to be nice and has had bodywork done to it, typically the move would be to block it with 180-220 and reprime. 320-400 would be more like if you were planning to seal it and paint it directly.
 
crashtech said:
It really depends, but if this is the first primer on something that has to be nice and has had bodywork done to it, typically the move would be to block it with 180-220 and reprime. 320-400 would be more like if you were planning to seal it and paint it directly.
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It went like this- bare metal, epoxy, filler work, light coat of ever coat G2 blocked in 180 then one more round finished in 220. and now this coat of epoxy.
 
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