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XTC-3D Epoxy Coating

The striations inherent in the DIY-grade 3D printing process don’t bother me all that much, but I got some XTC-3D epoxy to see what I’ve been missing. The impressive scrap pile from the badge reel holder provided test pieces:

XTC-3D Epoxy - test pieces - holders

XTC-3D Epoxy – test pieces – holders

If I were serious, I’d figure out a better way to hold the parts. For now, I jammed a watch crab into the back and trapped the bezel on a watch holder, but … ick.

Weighing the components seems the least-awful way to get the small quantities I need. The instructions recommend 100:43 by weight of resin (A) : hardener (B):

XTC-3D Epoxy - weighing pan

XTC-3D Epoxy – weighing pan

For these tiny parts, 2 g + 0.9 g was way too much and 1 g + 0.4 g seemed entirely adequate. If you slowly drool resin into the pan, drool slightly less than half that much hardener, and it’ll be about as close as you can get. The hardener is much less viscous than the resin: drool carefully.

The stuff might be self-leveling on larger parts, but on these small surfaces it’s better (IMO) to dry-brush multiple layers: you can see thicker and thinner sections in the first picture. The recoat time runs about 1-½ h.

The instructions recommend acetone or denatured alcohol as a thinning agent, at 10 to 25% of the resin volume, with curing times up to 24 h. Alcohol seems less likely to produce Bad Results, because it won’t evaporate instantly. Neither will affect PETG, but if you’re using another plastic, keep its solvent list in mind.

I tried alcohol with a by-weight amounts around 0.7 : 0.3 : 0.3 g, obviously overshooting both the hardener and the alcohol by a few drops. The end result resembled thick water, brushed on easily, and penetrated the surface easily.

A first coat of thinned epoxy should fill voids and unify the surface without changing the dimensions very much, with subsequent coats leveling the striations.

More pix after more layers and more curing …

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  1. #1 by TravelingServiceMan on 2017-05-04 - 08:12

    I’ll be interested to see your results. I wonder if that isn’t just urethane resin, neatly packaged. Since they advertise their colorant das urethane tint. Would be interesting for those of us here on the other side of the pond who pay a premium on top of the premium. ;-)

    • #2 by Ed on 2017-05-04 - 13:45

      The MSDS says it’s epoxy and it definitely smells that way, but I don’t see anything particularly special about it. In fact, they mention that it’s slightly yellower than their “Tarbender” table-top-coating clear epoxy, although AFAICT it’s less yellow than ordinary “clear” epoxy.

  2. #3 by jim oslislo on 2017-05-04 - 10:02

    I’ve tried this product on a few of my parts and considering the effort, time required and final result, my takeaway was that there has to be a better way.

    • #4 by Ed on 2017-05-04 - 13:48

      Aye!

      If I were making presentation-quality art objects, rather than techie tchotchkies, I’d be more enthusiastic. Then again, I’d also need the manual skills required to create high-quality surface finishes, rather than my usual bash-to-fit, file-to-hide, skip-the-paint techniques.

  3. #5 by solaandjin on 2017-06-13 - 04:03

    I’ve been playing around with epoxy coating some more lately. Ratio is actually 100:42, not that it matters. And an oven set to 170 F (the lowest mine will go) cures it fully in 15 minutes.

  1. XTC-3D Epoxy Coating: Results | The Smell of Molten Projects in the Morning

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