I forgot that part, definitely wear a mask! And not it in a well ventilated area.
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Hi there! You are very right that XTC-3D is expensive! XTC-3D, also know as Smooth-On, is really just an epoxy resin with a fancy name. That being the case, I’ve had great success by using other epoxy resins that are available at home improvement stores or Amazon. I’m really partial to this one https://www.amazon.com/Clear-Epoxy-Encapsulating-Casting-Gallon/dp/B00IT0APVM 656, and as a nice little bonus, the epoxy includes UV inhibitors so it won’t yellow that quickly and protects the PLA a bit.
For finishing PLA, I start with 80 grit sandpaper (60 is too abrasive for most part in my opinion, but I will use it if there are noticeable flaws) and work my way up to 400 grit (80, 120, 200, 400). From 400 grit to 1000 grit (400, 600, 800, 1000), I wet sand to prevent buildup of heat in the PLA . I just stick the part in an appropriately sized bowl/container and sand the part under the surface of distilled water, and change the water between grits or when it becomes dirty. After sanding, I clean the part with water and coat with the epoxy resin. If the color of the part got to distorted while sanding, I’ll very lightly apply heat with a heat gun until the color is restored.
Is this a lot of work? Yes, but it produces really nice results.
1 month later
Sanding, definitely sanding. But WET SANDING. It keeps the paper from getting loaded up, and it cools the plastic. (If you try to sand PLA too aggressively, it’ll get too hot and the dust loaded up in the paper will actually fuse itself back to the part, making it feel all crusty!)
Here’s what I do: just have a tupperware type container or some other sort of small bucket or tub on your workbench with water in it, and keep running your sandpaper through it to rinse the particles off, periodically dunking the part, wiping the part off with a towel, and wetting it again… Obviously you’ll need sandpaper that can take being wet. (I use 3M Wetordry, their automotive sandpaper…another benefit of this is it’s manufactured to produce a much more uniform scratch pattern.)
If you’re printing at 0.2mm or smaller layers, you probably don’t need to start with 2xx (200, 220, 250 are common, depends on brand) grit and can get away with starting at 400… Then it’s 800, 1000, 2000. If you want to get really super-shiny you can try 3M Trizact in 3000 and 5000 grit. (You should be able to achieve a mirror finish at this level.)
Of course, this is just if you want to polish up something printed-in-color, as-is… Painting is a much more practical approach, because a good high-build automotive primer can take most of the work out of surface prep. Example: (Skip to 2:57) Prop: Shop - Mister Handy Scale Model Build - YouTube 258 (Although this is about making a mold master from a 3D print, you can skip the molding/casting and just paint it at that point…you get the idea.)
28 days later
3 months later
I have been having a lot of success with warm Epoxy resin on PLA (I haven’t tried it on ABS as PLA is my primary filament). If you use it directly form the mixing bowl its way too thick. By adding 10 degrees of heat the epoxy starts to run like thin honey. Too much heat and it forms lumpy skins.
An additional process is to use a VERY low power blowtorch - I use those little modellers pen-like blow torches - and wave the flame lightly back and forth over the epoxy resin you have just laid-down. This softens the epoxy and smoothes it.
Obviously this doesnt work on smaller or thin elements but works very well on everything else. Its easy to sand afterwards.
11 months later
May I ask your detailed procedure? How to heat resin? Use hot water or heat directly? Do you heat the resin before or after mixing the hardender? Thanks.