I found this set of 3M Bondo plastic spreaders (#357) at Home Depot the other day for about $5. They are perfect for gently scraping the PDMS surface to remove any adhered resin, and to expose the surface to oxygen as has been suggested in other posts on this forum.
The plastic is slightly soft and the edge is perfectly smooth. The ends are rounded off so you won’t gouge into the PDMS layer. The three different sizes come in handy, too. The largest size fits the tank with about 1/4" to spare. The smallest size works great for scraping without forcing resin out of your tank.
Resin had been sitting in my tank for about a month without any prints being done so it had settled out. When I started scraping the PDMS layer there was a whiteish layer adhered to the bottom. It only took a few minutes of gentle scraping to completely remove this and the end result was a perfectly clean, clear, smooth PDMS sheet. My resin also got stirred up in the process and the next print came out fine.
Give it a try.
I second this. It is a great tool to have!!
That’s a great suggestion – we’ll pick up a few for the office! I wonder if this would be a useful item to include in the finishing kit?
Hi Sam. See what your team thinks about it after they give it a try. I think these scrapers would be great to include in the finishing kit because it’s a necessary procedure to do on a regular basis, and they will prevent accidental tears of the PDMS layer that could occur if people use the metal scraper included with the kit.
The reason I use the supplied metal spatula to “massage” the PDMS and expose it to oxygen is because it creates a tight seal when you drag it and scrapes all of the resin off the surface during the motion. If that makes sense. I don’t know how well a soft silicone spatula will accomplish that.
Great find! I had to step away from printing for a while (just too insanely busy at work these days,) but I’ll picking up a pack up tomorrow and, hopefully, Sienna and l will be back to printing again after next week. Thanks for the tip.
This is the scraper I use to freshen up the PSMS layer, it is very hard plastic with quite a sharp edge, I rounded the sharp corners off.