September’s blog talks about applying finishes to Onyx parts. Faced with a question I couldn’t answer from a customer, I disappeared off home for the weekend with the challenge of spraying one of the showroom samples a metal colour.

Having sprayed plastic before I was aware that there are problems getting paint to adhere to the surface and the damage that the thinners in the paint can do to the surface of the part. I’ve had some motorcycle parts suffer quite badly and I wasn’t sure how Onyx would react, so I gave it a go. As you know Onyx is quite stable and can be used readily in contact with machine coolant and hot water for long periods, so I was hoping it would spray well too.

A visit to my local paint supplier with the sample saw me dispatched home with an initial adhesion promotor (a self-etching primer) and a reminder to make sure the surface was completely free of any oil or finger prints. The adhesion promotor I was recommended was PlastiGrip Pro XL as it needed no further work afterwards and dried quickly.

I then made the decision not to do any mechanical preparation to the original printed surface for three reasons:

  1. I wanted a ‘straight off the printer’ painted part.
  2. Smoothing the surface would have given me ‘less adhesion’. The standard surface finish is great for painting and saves a lot of time that’s traditionally spent etching or keying super smooth parts.
  3. I wanted to see what the area with support material would look like.

After a couple of coats of adhesion promotor, I followed up with some grey undercoat, which I quickly inspected to make sure it was bonding properly. Happy with that, 2 top coats of standard Honda swinging arm silver were applied, and then two coats of UV resistant lacquer saw the results shown above.

Onyx painted really well in my simple tests, so I don’t see any reason why it won’t in a workshop environment. I didn’t suffer any chemical reactions with the adhesion promoter, paint or lacquer. The support area was still visible through the painted surface, so perhaps next time I’ll do some prep work there, if it matters.

Feel free to give it a go yourself I’d like to see the results.