Is it possible to seam/paint week old silicone?

Hi, I cast a piece in ecoflex 30 last week and had serveral failed attempts at seaming possibly due to "latex free" sponges (used to texture) contaminating my work, plus the patch that did set up did not stick. I had cleaned it thoroughly  with acetone. Now a week has passed. Is it possible to clean with alcohol or some other substance and have my seam and paint stick or do I need to start all over since the 72 hr cure window closed?

Question 2: is there a tutorial on silicone seaming? I can't find one. Any help is much appreciated!

Best Answer

  • Answer ✓
    Hi Paul,

    seaming older silicone can be tricky.  You may be able to clean the surface with a more aggressive solvent like Smooth-On's NOVOCS or Naptha to soften it up a bit and get a better bond.

    We don't have a class that focuses specifically on the seaming process.  We should cover that process in more depth in a future lesson.




  • Hey Paul,
    As Chris mentioned, once you get beyond the 72 hr. window, using your original material for patching and seaming IS tricky - especially with nearly sticky ones like eco 30. But switching to another silicone product can, and has, worked in our shop outside the 3 day mark.

    We've had success with sil poxy and psycho paint for both gluing and seaming, respectively, even after a week or more. Both can be tinted to your casting color using whatever you tinted your eco with initially, and thinned with naptha for a gloss finish, or novocs for a matte one.

    I'm not at liberty to divulge all our seaming techniques, but that psycho paint has a fairly long pot life that's even longer mixed with naptha or novocs, and a decent workable gel period will give you a good start. A little testing for set times and different texture sponges will go a long way here!

    Also as Chris mentioned, REALLY scrub your piece down with naptha or acetone before joining, seaming or painting, asafp before doing any of it.

    Good luck! 

Sign In or Register to comment.