White nylon yellowing?

Discussion in 'General Discussion' started by tempusr94720_c557488ae6c, Nov 28, 2011.

  1. The subject more or less describes the problem.

    The white nylon inevitably turns yellow as time passes.

    Why does it happen? Exposure to sunlight? Exposure to the air? body oils? Why?

    How can it be prevented? I was thinking about putting a thin urethane coating over the part. Would this help to seal the nylon, and make it so it does not turn yellow?
  2. nervoussystem
    nervoussystem New Member
    exposure to UV light

    an anti-UV clear coat will prevent yellowing
  3. Hey Nervoussystem,

    Thanks for the info!

    Do you know of any anti-UV clear coats that are on the market?

    What is the best way to apply the coating? Spray gun, paintbrush, dipping in a bucket of the coating?

  4. roofoo
    roofoo Well-Known Member
  5. stannum
    stannum Well-Known Member
    Artist acrylic varnish will do, ask in art shops for the pots/bottles (Winsor, Liquitex, Vallejo, etc). First coat, water it down a bit more than normal, then dip in it and the material will drink it. Use a plate and a brush, no need to buy a bucket of varnish to give it a bath. Other layers can be applied with paintbrush or airbrush.

    White paint will also work, and can give you a stronger white, but reduce the translucency. Or any other acrylic color, if you want.
  6. Wow guys, thanks so much. This was extremely helpful.

    Do these coatings help to waterproof your parts and make them more resistant to getting dirty?

    Also, do they help to take away the abrasiveness of the material? As I'm sure you know, the SLS white (strong and flex) has a "grain" to it. This can be a little abrasive on the skin. I'm making a wearable product, so this can be a bit of a problem. Do you think if I added enough coats of the acrylic varnish it would help to smooth out the grain?
  7. roofoo
    roofoo Well-Known Member
    The floor wax won't smooth the model's texture. For that I would recommend getting Shapeways WSF polished material. Not sure about the varnish.
    Last edited: Nov 29, 2011
  8. stannum
    stannum Well-Known Member
    Yes, they will become watertight and stay clean, as you are filling the pores with the first coat(s) and then building an outer shell. If you apply a thick enough protection, the sandy texture will fade (as well as any fine detail). You can look up in one recent post in which someone used glue to achieve a similar result than with acrylic varnishes.

    You can just order WSFP if you want to save some time with the smoothing steps, as roofoo suggests, but you will need to coat it anyway to avoid the yellowing problem. Remember to wash WSFP perfectly, someone else has complained about paint not sticking (the polishing uses soap).