minimum flash time of reduced epoxy before base

A

aviator8

Promoted Users
Im in a bit of a time crunch. I want to spray reduced epoxy sealer then move to base today. The perfect paint job states 4 hours. Can I get away with anything less, or do I just need to push out so I can wait the 4?
 
Jim C waits much less time when reduced 50%. Almost wet on wet.

@Jim C will hopefully weigh in.

I think the key here would a medium wet coat and not too heavy. If you are a novice or spray heavy I would follow the TDS. Better safe than sorry.
 
These are "safe" times. You can probably push it a little either way. Especially on the max times. Minimum times not unless you really know what you are doing.

10% reduction, absolute minimum 4 hours. Recommended 10-12 hours. Maximum around 18 hours

25% reduction, absolute minimum 2 hours. Recommended 6-10 hours. Maximum around 16 hours

50% reduction, absolute minimum 20-30 minutes. Recommended 1 hour, Maximum around 4-6 hours
 
Chris_Hamilton said:
These are "safe" times. You can probably push it a little either way. Especially on the max times. Minimum times not unless you really know what you are doing.

10% reduction, absolute minimum 4 hours. Recommended 10-12 hours. Maximum around 18 hours

25% reduction, absolute minimum 2 hours. Recommended 6-10 hours. Maximum around 16 hours

50% reduction, absolute minimum 20-30 minutes. Recommended 1 hour, Maximum around 4-6 hours
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Would Higher temps reduce these times any? Im gauging when to spray later. Makeshift booth is close to 100 inside.
 
Not really. If we were talking about urethane sealers then yes. But with epoxy while it likes heat, it doesn't affect the cure times in the same way as urethanes, UV light would speed up the cure but not heat alone.
As an example, with your temp if you can stand the heat some, I would go about it like this. Early morning apply one coat 25% reduced epoxy sealer, done by say 6:30 AM. Come back in the early afternoon and begin spraying base. Start approximately 1:00 pm. Apply clear the next morning.
 
Chris_Hamilton said:
These are "safe" times. You can probably push it a little either way. Especially on the max times. Minimum times not unless you really know what you are doing.

10% reduction, absolute minimum 4 hours. Recommended 10-12 hours. Maximum around 18 hours

25% reduction, absolute minimum 2 hours. Recommended 6-10 hours. Maximum around 16 hours

50% reduction, absolute minimum 20-30 minutes. Recommended 1 hour, Maximum around 4-6 hours
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Curious where you found those recommendations. Or are these your personal recommendations?

Don
 
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For my intellectual curiosity, what are the potential problems with going short or long on times. For example if you shot base over sealer 25% reduced at the 1 hour mark? I would think that you would get a stronger chemical bond that way, but I dont know. Or is it that the reducer has not had time to gas off and you'd get trapped solvents? On the long end is its downside a potential loss of adhesion? Also Im unclear why recommendations for open window would be different just by adding reducers. Isnt epoxy epoxy and the cure times are the same, its just the offgassing of the reducer that is different? Curious mind.
 
You are correct that you need to allow adequate flash time.

By adding reducer you are literally altering the chemistry, and this will affect curing times.
 
Lizer said:
You are correct that you need to allow adequate flash time.

By adding reducer you are literally altering the chemistry, and this will affect curing times.
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So adding reducer accelerates cure time? It would seem that way if 25% reduction vs unreduced epoxy is an open time of 16 hrs vs 7 days.
 
dhutton01 said:
Curious where you found those recommendations. Or are these your personal recommendations?

Don
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Just through using the products, reading here on the Forum, and talking to Barry on the phone asking him questions. Like I said they are what I have found to be "safe", not absolute hard limits.
 
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RosharonRooster said:
I may or may not have sprayed base, 15 mins after 1:1:1 epoxy sealer in 90 degrees on small stuff.....
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Jim C has said it was OK to go to base in 15 minutes after spraying 1:1:1. I didn't feel comfortable recommending that in my list above though. Too many variables for someone new to this.
 
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