The following is what I’ve tried that works on my Form1+:
NOTE: The silicone inside the tank weighs 64 grams (I weighed two of mine). If you are interested in dimensions of the silicone removed - the outside square is approx. 6.5” and 0.80” deep. The inside square is approx… 5.38” and 0.110” deep.
I purchased Slygard 184 silicone from Amazon.com. http://www.amazon.com/Sylgard-Solar-Encapsulation-Making-Panels/dp/B004IJENBG/ref=sr_1_1?ie=UTF8&qid=1421607096&sr=8-1&keywords=sylgard+184#product-description-iframe
Remove current silicone from bottom of the used tray by picking at one corner and pulling it up. It comes out pretty easily.
NOTE: Sanding the edges of the inside bottom of the tray outside the print area may help the silicone to adhere to the tray bottom. I have had the edges peal up on mine but not in the printable area. I’ll try sanding the next one to see i4 that helps.
Clean everything with soap and water and a clean microfiber cloth. Make sure the inside surface of the tray is perfectly clean before proceeding.
NOTE: Minimize exposure of the silicone to dust and particles. Keep the work area very clean and place the tray cover over the tray when you can.
Mix 80 ml of Slygard 184 per mfg instructions in a 1 liter container. You will need 65 ml per tray and you can’t get all of the silicone out of the mixing container so you have to mix some extra.
NOTE: Pouring 5 or 6 trays at a time saves you the wasted silicone that doesn’t come out of the mixing container so you will get around 6 tanks per 16 oz of Slygard 186 if you do them all at once. You should get 5 if you do them one at a time.
Degas the silicone in a clean, dust free, vacuum chamber for 30 minutes. The silicone volume will expand approximately 10x so make sure its in a large container so it doesn’t overflow.
NOTE: Place the tray cover over the tray at an angle so that it can’t form a seal. Otherwise, when you let air back into the chamber the cover will implode into your tray.
NOTE: It may be possible to get all the bubbles out just by using a heat gun. I’m not sure. I’ll try that on one tray during my next round of refurbishments.
Ensure the bottom inside of the tray is clean and clear. Place print tray on a scale accurate to 1 gram and pour 65-70 grams of mixed Slygard 184 into the bottom of the tray.
Place the tray on level surface. I suggest making a level place on a counter and marking it so you can use the same spot every time and not have to check level every time. Put tray cover on the tray and let the silicone level and allow bubbles rise near the top for 15 minutes
Remove the cover and use a heat gun over surface of the silicone and surface bubbles will pop instantly. Don’t hold the heat in one place for long. Just enough to pop the bubbles. Its very satisfying to see how quickly they pop.
Once all of the bubbles are gone allow at least 48 hours at 70F or higher for the silicone to cure.
NOTE: I placed the tray in a 150F a Nuwave Convection oven for a few hours to accelerate the cure time of the silicone. I didn’t want to go higher for fear of damaging the acrylic in the tray. Remember, the tray has to be level wherever you put it while its curing.