Today my buddy JW and I started going down the primer rabbit hole, and thought we would attempt some completely non-scientific, testing of the primers we have. This test is purely based on our initial impressions, nothing more.
So on hand, we have the following 3 (self-etching) primers.
- SEM – Self Etching Primer (p/n 39683)
- PPG One Choice – Etch Prime – Gray (p/n SXA1031)
- Sherwin Williams GBP Self Etch Primer 988
For the testing we sprayed a test strip of each and let it dry for roughly 5 minutes. Then using our fingernail, we attempted to scratch at the primer to see how durable it was. I should also add that the metal was prepped in the area of the test strip with a quick scuff with Scotchbrite and a wipe of acetone before we masked and sprayed.
Starting with the SW GBP 988, below is the test strip.
And here is the scratch test result. Quite frankly, it scratched quite easily, but didn’t go right down to the metal.
Next up, here are the other two test strips for the SEM on the left and One Choice on the right.
The PPG One Choice on the right scratched easily and scratched down to the metal. The SEM on the left was definitely the most durable of the three primers tested. It barely left any markings of the scratched surface.
What I find interesting about this test is that historically the Sherwin Williams GBP 988 has been my favorite primer to use, however here in Edmonton, I have a real challenge getting it, so a few years back I switched to the SEM product.
What does this mean, well, all in all it gives me a boost of confidence that the primer I’m using is at least adequate for the task at hand. As our testing ended here, I really have no further data to provide if these primers get harder over time as they cure over the next 24 hours or so. Who knows? Take our testing for what it is, a couple of airplane builders working out of a garage doing some spur of the moment testing.
That’s all for today folks! Please comment. I love to hear from my readers. Thanks again for coming along for this ride, you make my work worthwhile.
Good day!
I’m sure you are already well down this path. I’ll just mention that I’m going to use Cerakote C-Series instead of primer.
Thanks for your comment. I’m definitely committed to this path. I’m not really familiar with Cerakote, but it is something I can learn more about and see if it’s an application that might work for me in the future. At this point (and as soon as I’m done the wings) I’m going to be done with using rattle cans of self-etching primer. The cost is getting to be way too much ($36/can!). So moving forward Cerakote or just the standard 2-part epoxy primer is the direction I’m going to be leaning into.