Ever Seen This?

Hello fellow engravers. I've been using Thermark for about 10 years now. I did a sample piece of solid brass (C260 Cartridge Brass) about 5 years ago and then put it outside in the weather to see how it would do. After the five years I decided to clean one portion of the brass with a vinegar, salt and flour solution. Basically you just apply it, let it set for and hour then rinse off. Well it did a good job as you can see from the photo attached but the only issue is the Thermark came off as well. When I put it out there 5 years ago the Thermark was bonded. I believe it bonded because I used a metal polish (Mothers) to polish it afterwards. Can you guys take a look and give me your feedback on what you think might have caused the Thermark to come off?

Thank you for any feedback.

Just a theory here; the tarnish is a form of corrosion, and I don't believe Cermark to be impermeable to water, air and such, so while it bonded with the brass in the beginning, the layer of tarnish, like rust does with paint, compromised the bond.

Maybe after 5 years the weather had something to do with breaking down the bond, Sun, cold, acid rain. Who knows what else.

Quote:

---

Originally Posted by Kev Williams

Just a theory here; the tarnish is a form of corrosion, and I don't believe Cermark to be impermeable to water, air and such, so while it bonded with the brass in the beginning, the layer of tarnish, like rust does with paint, compromised the bond.

---

Thanks for the feedback Bert and Kev. I believe your right. Although it's bonded initially to the metal, Thermark is not a sealed product which means corrosion can get through to the metal it's bonded to. I'm guessing that the only solution is to seal the brass with a clear coat.

I think I know the answer to this but is there a possible thermal marking material like Thermark that holds up better to corrosion?

You are bonded to the brass that corroded. So the lettering came off as corrosion. 5 years, decent time in the weather for something like cermark on brass. Heck I can't get 5 minutes in my trials.

Everything wears out-- I've seen many a car and boat who's paint & gelcoat looks like crap after 5 years ;) - And honestly, until you gave the metal an acid bath, the Cermark STILL looked good!