casting plaster

today, i got to play with plaster casting in a clay mold.  i haven’t messed with plaster since i did my handprint in, oh, second grade summer camp down at the pool.  it’s fun.  i love casting in molds.  i learned how to sand cast a candle when i was older.  it was great.  i made a huge candle, i forget if it was green or blue, and put three wicks in it, because three is a magical number.  and then i put it on my dresser at home.  my dresser was actually my mom’s big old doublewide dresser with the huge mirror that stretched the full width of it.  by the time i made the candle, mom and dad had taken over the play room and made it their huge enormous garden level bedroom, and i, being oldest, and it being my turn, got to live in the master bedroom upstairs.  so i had the furniture.  and it was good furniture, not like they make nowadays (whine).

anyway, i had the candles lit and was putting on my makeup (yes i did, once), and waltzed out of the room for some reason, to go down to the laundry room to find my shirt, i don’t know.  by the time i got back, the wooden frame of the mirror was on fire at one end, the end that was directly above my candle, whose three flames had combined to make one huge flamethrower.

so, i nearly burned down my mom and dad’s house because i learned to cast.

but that’s okay, i almost burned down my current house while steaming silk – twice.

it’s the artist, not the materials.

jim pushing powdered plaster into the water

jim showed me how to do it.  he taught me the way his sculpture teacher taught him back in the day.  first he had me put on my apron (thanks jim), then get a bucket of warm water (for my hands’ sake).  and then we spread some paper towels.  you can see the huge big sack of plaster of paris on the right.  it was under the table in the middle studio, and i had to move a bunch of tarps to get to it.  and it was heavy.  as fine as really fine flour.

jim scooped 3/4 of a container full of water, which turned out to be too much.  then he took a scoop of plaster and sifted it into the water, so it wouldn’t clump too much.

the plaster falls to the bottom and silts up

when the plaster started piling up in the middle of the water, there’s probably enough in it, he said.  and when he put his hand into the container to mix the plaster, it overflowed, so we poured it off into the second container and i started another batch of plaster myself.  handsfull of plaster, sprinkled into half a container of water.  mine was much weaker, more liquid, than jim’s.  he went ahead and poured his in while i was still mixing mine.

it only takes a minute to put your hand in and squish the plaster together until there aren’t any more lumps.  it feels like jello as it thickens.  it heats up, too, an endothermic reaction between gypsum and water.  so when it starts to heat up and get thick, it’s time to pour.

just poured on left, 3-4 minutes old on right

jim’s is on the right, and i’ve just poured mine into the left mold.  his has already begun to set, because you can see the fingerprints i put in to test it.  mine is still very watery, with water separated and flowing above the rest of the plaster.  while jim’s was in the middle of setting, kind of hard to the touch, i noticed that the plug i had left for the drill was uncovered, so i took a finger and swept some plaster over that way.  it liquefied the moment i touched it, the way cornstarch does when you add just a little water.  kind of a solid and a liquid at the same time.

then i mixed up a final batch of plaster and poured it into the paint can at the foot of the dolphin.  it only takes up half the can, so i might put another layer on when i put plaster in the paint tray – but i can’t do that until my roller is finally dry.

as for the polyurethane on the brushes, i’m still trying to get enough on the spongy things so that they get hard and stop squishing when i press a thumb into them.  it won’t do to have them still flexible when it comes time to paint and varnish, because that shit’ll crack under pressure, and i can’t have that.   so i’m waiting for the roller sponge to set up before i stick it into the tray and pour plaster all around it.  and that may delay things.  i’ve dipped it three times and it’s still spongy.  if it’s still funky tomorrow, i’ll seek expert help.  won’t be the first time.  i just love expert help.  i couldn’t do it without expert helpers.

when the plaster set, an hour later, it was still warm, but very hard and heavy.  so i gently peeled the plastilene clay away from it, and got two really hefty halves of drills for my troubles.  i started to clean the drill halves and restate their lines immediately with a carving tool, and it was some hours later when i bothered to match them up and see how they fit.

well, they didn’t.  trouble is, when i peeled off the clay mold from the actual drill, and smoothed the clay, and set the mold up mostly level to be cast, i didn’t bother fitting the two molds together to see how they fit.  really, i was not touching them as much as possible so i wouldn’t distort them or put an inadvertent fingernail into them or something.

but what happened was that my first mold was made with a thickish and cold layer of clay that not only didn’t take the details very well, with air bubbles and soft contact, but also didn’t hold together very well, because it was thinnish, and it sagged while it was sitting there waiting to be cast.  on the other half, i used very thin clay at first and then a top coat of thick clay, and it was thicker than the first mold.  this prevented it from splaying out under its own weight, and probably also under the pressure of almost a quart of plaster (that’s two pounds).

so, when i went to put the two halves together, one half was significantly larger than the other.  you can see in both photos, the one above and the one below, where one edge doesn’t match.  the bottom half spread out on both sides, and only resembles the other half in the handle and the snout.  sort of.

i guess i should have turned this photo.  oh well.  see how they just plain don’t match.  a further problem was that one of the molds warped sideways while the plaster was setting, and so there was a big curve in the flat top (the top that’s supposed to be level because it’s liquid).

so i took my carving tool and traced where the halfway mark was on each piece, which in one case was a nice 1/8″, but in the other case was more like 3/4″.  then i took my carving tool, one that looks like a scimitar, and started scraping the edge down toward the line.  when i had the edge trimmed, i went in with the flat of the knife and started planing the surface to get the rest of it flatter.  scrape, fit together, sigh, repeat.

eventually i had to deal with the vast size difference, so i did my best to hold the two halves together in the exact proper position, and started scraping down the side that didn’t fit.  using the smaller edge, i went around the drill and made both sides of the center lines the same thickness.  this required some work, and a lot of reshaping, and i still had to decide where to make the final ‘center’ line, which in this case turned out to be on one side or the other of the trigger and other center-line objects.  it seemed easier to join them where the slope changed anyway.

i figured out that it’s necessary to make the top surface, the center of the object, concave.  this is so the edges will touch.  then you can trim the edges until the whole thing fits together.  if you have a little space in the middle, there’ll be someplace for the glue to go without pushing the two halves apart.  and if they do push apart, just carve into the bond a little bit and run a bead of acrylic molding paste to fill it.  it won’t e noticed when you paint it.

a funny thing.  this plaster is dry, at least set.  it won’t cure for many hours yet.  but when i scrape it, the scrapings liquefy.  and the plaster that i mixed came up wet, like goopy, and i had to wipe it off with my fingers because the knife just spread it.  and when i gathered the excess plaster in my hand and started kneading it, it went from dry and crusty to soft and supple in a matter of moments.  very strange physical properties, wet plaster has.

ta dah

using the actual drill as the model, i went around with a spadelike carving tool and drew in all the details.  except for the ribbing and texture on the chock, and the name.  i mean, the drill has another city’s name on it, and i didn’t think that was right, so i wrote atlanta for the name of the drill.

it took a very long time, and was very detailed and painstaking toward the end.  but the plaster was very soft, and i could cut right thru it, and scrape it off into puddles, and carve stuff all i wanted, and the work went well, if not quickly.  this kind of art isn’t quick.  people who make models take donkey’s years to finish a project, but it’s always so wonderful when they’re done.  per hour they’re making maybe a nickel, but money’s never why they do it.  you work for love in this business, and money follows if you do what you love.  also comes the wisdom to play poor when you’re really rich.

i’m feeling much better 24 hours after i wrote how cruddy i was feeling, thanks for asking.  i’d taken most of the day off.  my right fingers were swollen when i went to bed, and i was still achy this morning, and besides, my daughter had a typical full-moon crisis and i was up and distressed at 4 am, which was only 2 hours after i’d gone to bed.  so i went back to bed right after the dog walk, and slept soundly until 2 in the afternoon.  ah luxury.  the grandbaby watched lightning mcqueen and then went with jim to the store.

by 3 i was down in the studio, so okay half a day off.  and it’s almost 2 now, so that’s still 11 hours.  i’ve been doing approaching 12 hour workdays for the last week or two, and i’m kind of tired.  so it was good to do something completely different today.  even if it didn’t mean any more sleep than usual, really.

i want to do a body cast.  one of these days.  i m going to continue doing breast cancer art, and this one is going to be a plaster cast of my chest with one breast and a mastectomy scar.  it’ll be – let’s not say gross – it’ll be striking.

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