The authoritative public forum
  for Metal Finishing 1989-2025
  

  -----

Textured finish and mil specs

I am with an OEM for a defense contractor, and our application involves applying a textured finish to a knob or dial handle for added gripping ability. We cannot knurl the knob or dial handle. My first thoughts are to mix sand and paint and apply that after applying a primer; however, I know not of a military specification that allows a sand-paint finish. First, is there such a military specification? (I've been searching for a while and can't seem to find one.) Second, if there is no such military specification, is there a mil spec texture finish for the application?

Whitney Roberts
OEM Engineer - Westminster, MD, US
May 15, 2009

---

May 20, 2009

Unless I'm mistaken, mil-specs will only cover the mechanical properties of the coating and being a supplier you should already have them. So the spec you are looking for should describe something like this:

the coating must withstand X amount of salt spray hours
the coating has a scrape adhesion factor of X
the coating has xx degrees gloss
the coating must be chemically resistant to X

So if you mix sand into the top coat of paint and it meets the spec, you win.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina

Another plan would be to go for a spatter finish. Put a base coat down of the colour you want, then apply another coat but use a large fluid tip 1.8 mm/2 mm cut the air pressure down to <10 psi and do not thin the paint. You can practice on a bit of scrap. Basically you are applying a "bad" finish, but a heavy spatter like this will give a decent texture not much worse than knurling and you will not have any problems with sand.

Jim Rowbotham
- Halifax, UK
May 25, 2009