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Coating Adhesion on sanded vs. unsanded 1018 CR Steel
Q. Hey,
I work at a high end furniture shop, we patina all our visible surfaces, but for unseen we either spray with a black enamel plaint, or Dykem Opaque black.
I'm trying to establish metal prep procedures for parts and their corresponding coatings. I've been able to find all the surface prep requirements for our enamel paint, however Dykem seems to be seriously lacking in that area. The best I've gotten so far is "Apply to a surface that is clean, dry and free of oil and grease" from the Dykem technical data sheet. Will this alone provide us with a long lasting indoor finish on non seen parts?
My gut keeps telling me Sand it first. If that is the case is there any ASTM like documentation stating this?
Also if this helps, its not on their MSDS oddly, but it does contain Nitro Cellulose.
Metal Prep Supervisor - Philadelphia, Pennsylvania, USA
March 9, 2017
A. Hi Anthony. Indoor furniture is a relatively easy application with regards to corrosion resistance, so sanded vs. unsanded vs. pretreated probably isn't a big issue. Still, painted steel ideally would be phosphated.
Assuming the steel will remain without phosphate pretreatment, an advantage of sanding the steel would be that it will remove some soils and oxidation products which might otherwise be on the surface, and which could interfere with adhesion.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 2017
A. Hi Anthony,
I completely agree with Mr. Mooney and very light sanding would likely improve adhesion if cleaned afterward properly. A sanded surface at a microscopic level has a far greater surface area compared to a smooth surface. A greater surface area means more places for the paint to stick and hang on to!
Blake Kneedler
Feather Hollow Eng. - Stockton, California
March 26, 2017
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