Epoxy as sealer clogging sandpaper…thoughts?

R

RandyR

Promoted Users
Hey guys,
Quick question…painting my doors one side at a time. Painted the inside and came out good. Flipped over, masked off the painted parts then sprayed the exterior surface with reduced epoxy as sealer. Ended up with a few dust nibs so decided to do a quick block sand the next day. Blocking with 320 which is recommended by my paint brand PPG Delfleet Evolution single stage, but the epoxy keeps clogging my sandpaper…even now two days after the seal coat. Epoxy, activator etc all less than 6 mos old. Any thoughts on the problem? Thanks!!
 
I use an 800/1000 grit sanding sponge to remove sealer nibs. Just a quick wipe gets it done. 320 is pretty aggressive. How much did you reduce the epoxy? 48 hours is too long for reduced epoxy sealer afaik….

What temperature have you maintained in your booth?

Don
 
dhutton01 said:
I use an 800/1000 grit sanding sponge to remove sealer nibs. Just a quick wipe gets it done. 320 is pretty aggressive. How much did you reduce the epoxy? 48 hours is too long for reduced epoxy sealer afaik….

What temperature have you maintained in your booth?

Don
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320 is recommended by PPG for this particular paint. I was surprised too but what I’ve sprayed so far looks great.
I know reduced epoxy should receive paint within 24hrs but I haven’t been able to smooth out the dust nibs because it clogs my sandpaper. Just trying to figure out why I can’t sand it yet. My booth temp is probably 65-70 but goes down to 50 at night when I’m not here. It’s probably all temperature related.
Thanks for your response
 
crashtech said:
50° is way too cold for the epoxy. I keep my shop warm enough to ensure 65°+ surface temps 24/7 when there's freshly sprayed material around, which is pretty much always. An infrared thermometer is mandatory.
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I don’t really have a choice. Working in a friends large warehouse with an inflatable paint booth. A couple of 1000 watt halogen lights warm the booth pretty quickly but I can’t leave them on overnight. When shooting epoxy I try to keep it warm for a few hours before I shut things down. I have an infrared thermometer to make sure surface temps are 65+ before spraying
 
Chris_Hamilton said:
If you can't keep it warm for the required time it's better not to use it. Reduced you can probably get away with what you described, but when shooting it unreduced you can't.
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It’s been working fine, but we’ve had unseasonably colder weather for SoCal for last couple of months…it’s slowing down my progress…argh!
 
RandyR said:
Are you saying it goes dormant at 50 and won’t resume hardening when it warms up the next day?
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Epoxy is different than 2ks in that when temp up the next day will pick back, and epoxy
Can take 2 days at 70 or more to start up again.
If curing in cold causes it to create its own alcohol it will never cure at even 400 degrees.
 
Barry said:
Epoxy is different than 2ks in that when temp up the next day will pick back, and epoxy
Can take 2 days at 70 or more to start up again.
If curing in cold causes it to create its own alcohol it will never cure at even 400 degrees.
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Thanks, Barry. Is this true for all epoxies or just SPI?
 
All epoxies made for auto refinishing
Special ones made to cure outside and cold weather this don't apply.
Reread ass-u-med you were referring to forming alcohol.

So to correct myself I think you are reffering to pickup on curing.
No does not as there are a 100 ways to make epoxy and there are some that are really thin and cant sand.
 
I appreciate all the responses! I'm a hobbyist and long-time car guy doing a total rebuild on my 66 Ford F100 shortbed pickup. The build includes a Coyote swap, suspension swap, boxed, beefed up chassis, media blasted entire body, shot with multiple coats of SPI epoxy, did all the body work, more epoxy, turbo primer, etc.
I was introduced to SPI around 15yrs ago via the Club Hotrod forum where guys like Shine swore by their products and quality of the company. I became a huge fan based on the experience and testimonies of many of you guys with tons of real world experience even though my own experience has been somewhat limited. There is definitely a learning curve with using epoxy. I had some spraying issues a while back that you guys helped me with. I got those sorted out and things have been going great until this recent encounter with a seal coat. Oddly enough, a few days before on some other parts, I mixed up the epoxy 1:1:1 per someone's experience here on the forum (I forget who). I sprayed the seal coat and shot the paint over it after an hour of flash time. It turned out great. As stated at the top of this thread, using that same method didn't turn out the same on the exterior of the doors. I have most of the truck blocked out and ready for paint. I'm just trying to figure out how to resolve any more potential issues with using the reduced epoxy as a seal coat. A few warmer days are in the forecast, so hopefully that takes care of most of it. Thanks again!
 
Here’s another question about epoxy and temperatures…let’s assume both booth temperature and metal surface temperature is at least 65 degrees when the epoxy is sprayed…how long does the temperature need to be kept above 50 degrees to keep it from going dormant? 8hrs? 12hrs? 24hrs? Just curious about a safe range…
 
RandyR said:
Here’s another question about epoxy and temperatures…let’s assume both booth temperature and metal surface temperature is at least 65 degrees when the epoxy is sprayed…how long does the temperature need to be kept above 50 degrees to keep it from going dormant? 8hrs? 12hrs? 24hrs? Just curious about a safe range…
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Not sure where the 50 degrees is coming from. From the tech manual:
CE29C301-A84F-41EC-A0F9-BECA41D9C97C.jpeg

Don
 
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