I've commented on this video previously but couldn't find it. I stumbled acrossed it again today. I haven't done any lost PLA casting and for larger parts am still firmly in the camp of lost foam being more practical (at least for me) but for organic shapes like this and those that can 3D print, it's a powerful technique. The video and cast is total folly but with some adjustments could have merit. I think reason his first pattern dip had runs was because the PLA pattern was too cold. Now, there might be problems keeping the pattern dimensionally stable at higher heat but I bet the parafin temp could be reduced substantially if the pattern was at a similar temp before dipping. There may be additional benefit in having the thin layer of parafin for reducing mold stresses during burn out. For mold making he's using a sand and PoP/plaster mix. Many are critical of this as investment but it has been successfully used by art casters for years. He just needed to anchor the pattern in the mold better than he did and be more methodical about his mixing methods.......and he would have had a good mold. He should have stopped and fixed the mold but did not and consequently the ensuing pour was also pure folly. Best, Kelly
Agree its kind of a good concept poorly executed. Previously I played with mixing paraffin and toilet ring wax to smooth over white foam beads. I spread it with a tongue depressor but it still left streaks. It was a large foam skull. But I wondered if there was a right mix that would melt below the foam's melting temp that cold be dipped in. Hm, makes me want to do some experiments now.
I've used paste wax (Trewax is the brand I have) to fill in/smooth out the foam bead texture for lost EPS foam casting. Worked well for me. I just smeared it on and smoothed it out with a fingertip after working a small chunk by hand to warm it up and soften it a bit. Don't try to fill wide gaps or build up mass this way, it'll run like too much spraypaint, over the surface of the pattern, away from the metal front, which may become visible on the surface of your casting. Pour or dip soon after adding this type of wax, don't give it time to dry out and shrink and start to flake away before the part is poured or at least the pattern's coated. Results from my attempts with some easter bunny foamies are shown here: https://forums.thehomefoundry.org/i...for-cheap-lost-foam-patterns.1011/#post-24640 Good luck & let us know if you try this! Jeff
Might try the Treewax when I get up and running. Couldn't find a photo of applying my wax mix but did find the finished product. I still did some sanding and polishing but the beads were smoothed out by the wax. The one on the right was straight out of the sand and cleaned.
