What is the finger nail test?

highvolt

Promoted Users
I feel stupid asking the question but want to make sure I'm assuming correctly.

Just opened the activator for the epoxy primer but label on can is dated three years ago. So I sprayed three coats of the white epoxy on a scrap piece of metal (12"x12") waiting 30 minutes between coats after inducing 35 minutes. It sprayed out great and looked more like paint than primer. For the first 12 hours I could put a thumb print in the primer but by the 24 hour mark it was near impossible. Sprayed the panel in basement at 55 degrees but took upstairs in the house between coats and to finish drying at 68 degrees.

I then wanted to do the finger nail test. I could take my finger nail and dent the epoxy till about the 30 hour mark but it was hard. I then with great pressure was able to scrape a bit off down to bare metal. Was not gummy but I was able to scrap off.

So am I good or not and what am I looking for on the finger nail test exactly.

Have a great day,
Bob
 
I have no clue how to do a nail test on epoxy.
Pot life 2 to 4 days.
Adhesion can scrap off the first 2 to 4 days.
Any probably need to do it after a week unless you use it a lot and could figure it out in a day or two.
 
Bob, just thinking out loud here, the white epoxy seems to be the one that most have issue with learning curve, especially fish eye from spraying too heavy at first, etc. Yet you state it sprayed/looked like paint and not primer. Additionally, given product was three years old, I would have expected some sediment in the bottom of part A. Did you stir the epoxy fully?
 
Okay now I don't feel so dumb asking now. I thought the nail test was with epoxy primer.

Yes sanded and cleaned bare metal. Part "A" did separate but stirred with 3/4 x 3/4 oak stick till completely mixed then shook by hand. Sprayed out nice, orange peel a bit but good. No fish eyes or anything like that. I'm out of town till weekend so I'll try scrapping off then.

So this brings me back to the finger nail test. I've searched and searched this forum and can't find the proper way to complete the test only that it's good or fails. Please point me to a posting or provide me with detailed finger nail test would be greatly appreciated.
 
I have no clue how to do a nail test on epoxy.
Pot life 2 to 4 days.
Adhesion can scrap off the first 2 to 4 days.
Any probably need to do it after a week unless you use it a lot and could figure it out in a day or two.
Can you tell me what the finger nail test is for and how it's done?
 
I've been doing this a long time and I have no clue what test you are asking about. Using your nail to check if a clear or SS has hardened is about the only thing I can think of and it's not really a test, just an informal way to gauge if your clear or SS has cured past that point.
Why are you focused on this? Just curious.
 
Last edited:
I've been doing this a long time and I have no clue what test you are asking about. Using your nail to check if a clear or SS has hardened is about the only thing I can think of and it's not really a test, just an informal way to gauge if your clear or SS has cured past that point.
Why are you focused on this?
I was reading several older postings referring to a "finger nail test" and wanted to know/understand.
 
Mr Hamilton,
You started this! Screenshot_20230419-054552.png
 
Lol. :) Well if I spoke of something it was really just in the context of the post I was replying to. Not any sort of formal test.
 
  • Haha
Reactions: AAE
Back
Top