It is now Monday of week five and I have decided to make the entire positive over for a couple of reasons but I will let you read about last week first!
I started with a drawn template used to create some masonite forms cut on the scroll saw. The masonite allowed me to have a perfectly smooth tray surface and limited the amount of plastiscene (oil clay) I would need to create the positive. I needed the bumped separation part of the tray to be hollow and to be about the same thickness as the masonite (1/4") so I lined the masonite forms with tubing and started to apply plastiscene that had been rolled out to 1/4" over the tubing. After I had finished putting the oil clay over the tubing I spent a long time trying to make it smooth and without undercuts, undercuts would act like little locks on the clay when cast causing the clay form to tear apart upon removal. I probably spent two days trying to get it as perfect as I could...the better the positive the better the mold the less work you have to do on the clay when cast which is the goal...considering I need to cast this one hundred times a few days getting the mold as perfect as possible will save time fixing one hundred trays later!
After the tubing and plastiscene were in place and the pour gates added I coated the masonite in polyurethane to be sure it was watertight (if not the plaster would adhere to the porous wood) and let it dry.
The next day I cast side one of the mold, thankfully Robby Burton, our studio tech. was around because I couldn't lift the plaster/water mixture up myself in a way that would allow me to pout it in any sort of controlled fashion (it was a little over 50 pounds). The next day I came back, flipped the mold and removed the tubing so I could clean up the other side (what will be the back of the tray).
This revealed a challenge that I had not thought of, the removal of the tubing and the straight sides of the masonite left a very tight U shaped "tunnel", it was my intention to have a hollow channel (on the backside) separating the food areas of the tray but this one was going to be way too tight and narrow to successfully remove the clay cast and was to difficult to access to clean up the undercuts. So I did one of the cardinal sins of slip casting...I removed the positive before I had cast the other side to I could bevel the edges of the masonite, when I returned it to the mold this allowed for a much more open U shape...more like a hammock... I think it will work.
So then I set to work smoothing the plastiscene, checking for undercuts and putting polyurethane on the backside of the masonite, this took another full day. After casting the second side and letting it cure overnight I was able to take the positive out (in pieces) and spent the morning cleaning up the inside and outside of the mold. So far it all looked good, it was pretty clean in there, the positive seemed to come out with little signs of impending trouble and I thought I would just I wait until the mold was dry enough to do my first cast which should have been by the end of this week. Then when I lifted this gigantic and very heavy mold into the drying box I wrenched my back! The mold is so heavy and big I can really barely lift it. This was the first sign of impending doom! I had to spend the next two days and then over the weekend at home because of my back!!! Yuck!!! (As an aside, I spent the weekend thinking about my age and that I really need to reconsider the value of exercise time over studio time. My body needs to keep up if I want to continue working in this physically labor intensive field...which I do!)
In the meantime Robby has almost finished welding a killer vibration table! It looks really great, I think he is going to mount the motor on it soon! At home with my back out of commission I did some color tests on my casting slip. I want to try to cast the trays in an couple of different colors, I think it will look good, provide some variety amongst the trays, allow for consistent non-brushy color, (I have had some problems with uneven brushy application with some slips and I do not want that kind of mark making on these pieces) and limit the amount of time it would take apply two coats of slip to the front and back of one hundred trays! I am going for light colors, something sort of subtle that will tie in well with the already existing decals.
As of today (Monday) I have decided to make all new positives. When I got to school this morning I had spent a sleepless night thinking that the tray was really too big, the mold is so heavy and large I can barely move it myself and I don't really like the shape of the cup holding area. The straw that broke the camels back was coming in this morning and trying to do a test cast. The vibration table is not finished (Robby is on vacation) but I decided to give it a go anyway just to see what would happen, the first cast is always a waster/clean out cast anyway. As I started pouring the mold all looked fine until I was about half full, then slip started pouring out of the bottom and all over the floor!
I managed to get it filled anyway but I am almost sure it is not going to work! I think I need to pour with the tray on its side to allow gravity to work the slip to the bottom and throughout the mold but that puts a lot of pressure on those bottom seams. I definitely need more straps to hold it together and I may need to pour it flat so gravity works in the molds favor instead of the slips favor. Anyway it is very frustrating but I am learning through these failures. I need to get over the fact that I feel so rushed for time and just slow down and take the disasters in stride and move on. I'll let y'all know if the positive came out in any way close to the way it is supposed to look next week, and I will update you on the new smaller positives which I will thankfully be able to make much faster now that I know what I need to do and other progress by early next week! Wish me luck! I need it!
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