Casting resin and my problems with nightglow pigments

Discussion in 'General Slingshot Discussions' started by Knallfrosch, Oct 16, 2016.

  1. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    I like to experiment with new materials, colors and such.
    I am using casting resin for a while now making my own paper micarta
    and various colored sheets to be used as scales for slingshots of course:).

    At first i made a square casting form to make sheets and cut out the slingshot designs as usual boardcut.

    But in the longrun that was quite expensive because of the cut offs that
    cannot be used further and not all colors are nice enough to use them on a slingshot.

    With my blossom design my wish for more colors and experiments with
    casting resin grew stronger and i decided to make a silicone mold to cast
    a slingshot scale without the need of cutting it out of a full sheet.
    On the first picture you see the silicone mold made from my master-template.
    It only takes ~20ml instead of over 300 for a full sheet.

    So far so good.

    Color pigments usually mix perfectly with the resin forming a homogenous
    suspension resulting in a completely colored cast.
    But for some reason, nightglow pigments don´t behave like that.

    On my fist try with nightglow pigments i only got a thin layer of those on the bottom of the sheet.
    Next two tries i used different thixotropic powders to make the solution thicker
    ( one was recommended by the resin manufacturer for my problem )
    but it still doesn´t work. As you can see on the next pictures,
    the nightglow pigments still settle on the bottom of the casting mold
    and do not stay in solution.
    My goal is to imitate the nightglowing kirinite sheets that i recently bought.

    My last try with a 15 ml amount of resin i used a half tablespoon of
    nightglow powder and a teaspoon of the thixotropic powder and stirred for 20 minutes...
    it takes that long to make the pigments dissolve properly.

    My guess is, these pigments are heavier than normal color pigments.
    But there must be some way to keep them floating.
    If someone have any idea how to solve this, i would be happy:D.

    Thanks.
     

    Attached Files:

  2. bigdh2000

    bigdh2000 Administrator

    Thanks for all the information.
     

  3. Flipgun

    Flipgun Active Member

    3,811
    4
    38
    I seem to remember from somewhere/when of another builder having the same issue. I want to say that he mounted the form to a low rev shaft. (A rotisserie?) and the particles never had the chance to settle into a layer. I can't swear to this though.
     
  4. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    Hmm.
    Well thanks, i have to check, if i can do that with my equipment.:)
     
  5. Juggalo

    Juggalo My slingshots are like me. They aren't pretty.

    1,235
    0
    0
    Nice information i like that you are trying different things for home building
     
  6. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    Apparently i was to hesitant with the thixotropic powder.
    I tried another one with a lot of that stuff in it until the resin had the texture of thick toothpaste.
    I had to smear it into all the edges... but the result was encouraging.

    Also i found some more tutorials and they mostly use resin that cures within a couple of minutes, so that the
    pigments don´t have the chance to settle. I tried to compensate that with my 40-minutes-open-time-resin and put it in the oven for 45 minutes at ~50°C/122°F
     
  7. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    It seems that the "open time" of the casting resin is the key to a successful cast.
    I tried a different resin with an open time of 10 minutes instead of 40 mins.
    And voilà a completely glowing piece of resin :D.
     

    Attached Files:

  8. Juggalo

    Juggalo My slingshots are like me. They aren't pretty.

    1,235
    0
    0
  9. GunGuy

    GunGuy Active Member

    1,450
    0
    36
    Very nice, I just got 10 buckets of silicone mold material and was wondering what to do with it. Do you have to degas the resin when you make it?
     
  10. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    If you have a vacuum chamber, it is definitely better if you do.
    I don´t have a vacuum chamber, though.
    I have to sand away the cavities from bubbles at the surface, or fill them with clear resin.
    You can pop bubbles with a lighter flame as long as the resin is still liquid,
    but i often have tiny bubbles that tried to espace afterwards and just made it to the surface and
    were trapped there.
     
  11. Knallfrosch

    Knallfrosch Senior Member

    1,325
    26
    48
    After the successful casting, i had to do some blossom scales with this stuff.:D
    I saw a tutorial that stated a white background would enhance the brightness of the glow,
    so i added a thin layer of white casting resin to the glowing layer.
    Although its pretty bright, i need to think of something to make it more interesting... just glowing is not cool enough :D
    I strapped the two scales together back to back and powered it up with a flashlight... as you can see it is... bright.:D
     

    Attached Files:

    Last edited: Jan 19, 2017
  12. Juggalo

    Juggalo My slingshots are like me. They aren't pretty.

    1,235
    0
    0
    Oooooo shiney bright.