• The finished pool model

    Colored concrete bas relief panel for the new city pool building to be inset into the exterior concrete block wall by the entrance. The design has been discussed in previous posts last summer, the techniques on the original clay model which was  my own design based around the drawings of the actual pool  and walkway layout. The design incorporates raised letters which were executed on the clay model using some novel-to-me but time proven techniques for creating raised letters in sculptures found in a 1930s era sculpture book.

    The book suggested that such raised letters were almost never hand formed individually in the clay as they simply cannot be easily modelled uniformly and exacting, or without a lot of time. The technique I used was based on the 1930s concepts but modified for my situation and methods, essentially I purchased the required commercially made wood  letters, made a quick rubber mold of them as a group, poured the letters in different formula mold rubber, and then cast a plaster mold of the group of rubber letters. The plaster mold was then used to hand-press clay into, once the clay letters firmed up a little and could be removed from the plaster mold they were afixed to the clay model in their appropriate spaced locations already lightly marked out.

    The end result was perfect, every 1/4″ raised letter neatly and evenly shaped and spaced.

     

     

     

     

     

  • Art Deco D5

    The rubber portion of the mold is almost completed, one additional application in about an hour will finish it, then it will cure overnight and I can build the plaster shell for it to-morrow.

    Once I have the shell done it can be taken apart and removed from the plaster master and I can cast a new plaster master to store away, once I do that I should be able to start making the positive rubber master mold.

    I can finish the rubber positive master mold but I don’t have any more molding plaster with which to make the plaster press-mold, either I’ll have to order a bag shipped UPS or wait until I order some regular cast stone and clay and have some bags added to the truck shipment. I think I’ll just bite the UPS cost on one bag so I can get it done sooner than later.

    PICT3013

    Now with the new mold completed (above) I have begun the next step- making a positive/reverse mold of the inside of this negative mold.

    With the positive/reverse mold rubber applied to the inside of the first mold, it is now filled with plaster for the supporting shell, both the plaster and the rubber now set aside for a few hours for the rubber to cure (below)

    About 5 hours later with the rubber cured a little faster than otherwise due to the heat of the setting plaster, the first mold is removed leaving the positive/reverse mold with it’s plaster inside supporting shell (below)

    Now I have to wait on getting some molding plaster for the next step- making the 5 piece plaster mold of this, 4 side sections and the flat face section which will be used to press the clay into once that is fully dry.

  • Art Deco D5

    I have my master plaster cast taken from the original mold made from my hand-modelled 2007 clay master laid out on a board to prep for the new mold.

    I needed to do a little bit of repairs to the sides on this first, unfortunately the original clay model was fired in the kiln a year ago and for some reason I had not taken a plaster master cast from the first rubber mold immediately when it was made as is typical.

    That was probably because I had the original clay model, but later forgot I didn’t also have a plaster master and I fired the clay, as a result the original clay model is about 5% smaller from being fired and I don’t want to re-mold that since it is smaller than the other two panels in the set- one of which was fired the other was damaged beyond salvage to fire it but has a plaster master stored away.

    The master cast being used now was taken from the first rubber mold made of the  compound I used to use that started to tear and shrink early on, as a result the sides were somewhat uneven.

    Fixing that now and the mold will start to-morrow, once I have the new mold I can make the second mold I need to have to get started on a plaster mold for pressing terracotta from.

     

  • Terra cotta

    I now have my kiln back in my home studio after removing it from the gallery basement which seemed like the ideal place for it at the time I bought it. So it’s set up now at home where it’s much more convienient to monitor.

    I fired a couple of older raw clay original models with complete success, including the Astor Place subway beaver model which was just 1/4″ less tall than the inside of the kiln with the lid closed.

    I’m considering “converting” the Art Deco D5 model into a terracotta line, here’s the original clay model that I fired in the kiln a year ago after making the rubber mold for casting it in interior cast-stone and concrete:

     

    In order to “convert” it to enable making them in fired pressed clay, I would have to make a positive cast in rubber and then make a 5 piece plaster mold of that positive rubber cast. The idea of the rubber positive is the rubber is soft and “gives” so that pulling a hard plaster shell mold off it, undercuts slide right out easily.

    Once I have the positive rubber I can make molds from that as needed, making one to start with. When the plaster mold is dry then the clay can be hand-pressed into it, allowed to stiffen slightly, removed, dried completely and then fired in the kiln.

    One thing with the “converting” is that  in the processes there is about a 5% shrinkage of the clay from wet to dry and another 5% shrinkgage during firing for a total of about 10% or 1″ loss per 10″ which on this panel will result in it being about 2″ less wide and maybe 1-1/4″ less tall.

    I think this fall/winter I’m going to do this.

    Actually, I decided to go ahead and order the $200 worth of mold rubber I need to make the replacement mold for this since the original mold rubber by Quantum Silicones that I used in 2007 to make the first mold turned out to be total  garbage. Hopefully this weekend if the rubber arrives before Friday I will have the master cast all set up and ready to mold Saturday.

    I should have enough left over from the two gallons added to the left-over rubber I have on hand to make the positive mold too- on Sunday if all goes well.

    At least with this I can get the process started, I don’t have any molding plaster on-hand to make the press-mold with though, and the regular cast stone is not suitable for this as it hardens up extremely hard and is not absorbant as the molding plaster is.

    I might just get a bag sent to me  UPS as I don’t want to order a pallet load of material right now.

     

     

     

  • Various

    I have  the Nashville clients’ project finished, with the last two crates shipping in the morning, and the city pool projects’ concrete panel finished as well.

    The concrete pool panel turned out to be a major pain unlike any other! and to think, this is a donated sculpture and it was to be a simple matter to cast the concrete into the mold I made. After casting the first one there were two things I didn’t like, one was it had a lot of fair sized air bubble holes on the surface, the other was the acid stain I’ve used so well on many concrete casts absolutely looked all wrong for this bas relief- way too dark.

    Ok, so I decided to cast another one and use a different stain, same story there, lots of holes on the surface and the other stain didn’t look right either!

    So I cast a third one, this time I decided to nix the stain and go with an integral concrete color, but this one too despite my best concerted efforts also had a lot of holes in the surface! Concrete will always have some no matter what you do, but this went beyond the definition of “some.”

    So I re-examined the whole process to see what may have changed, then  I figured out there was only one thing I had changed from the usual and that was making use of my large powered concrete mixer to mix up the dry material. I thought about how that worked and realized it was almost certainly fluffing up the sand and Portland cement enough it was putting lots of air into it.

    So the 4th try I mixed the concrete up the normal way I have for years- by hand in a rubber tub, and I decided since panel #3 was not quite as red as I was hoping for, and that I had not used the maximum amount of color yet, that I would go ahead and add two bottles of it to the 12 quarts of water for the 150# of concrete to get it a little darker.

    The product can be used one bottle to 60# of concrete, I used one per 75# and kept it a little less than the maximum but more than the 1-1/2 bottles I used for #3.

    Now that it cured for a couple of days I took the cast out today and it came out good, a small amount of tiny air bubbles as normal/usual and certainly nothing like what I had with #1, 2 and 3. It looks like it will turn out to be a pleasant red terracotta color when it’s fully cured and dry.

    So now we know- stay away from any mechanical mixing of even the dry ingredients! I knew to stay away from mixing the wet concrete that way, but it never dawned on me mixing the dry ingredients would cause issues.

     

    Hopefully in a few days I can get a photo of the panel, meanwhile my right middle finger is feeling better, after having been banged a month or so ago and the nail turning black and blue, it was half replaced by the new nail when you guessed it- it was smashed again the other day wrestling the over 100# plaster mold for the pool cast down the  stairs, I lost my footing a bit and tipped towards the stone wall and of course that finger was the one that was between the mold and the stone wall and was half scraped along the rough stone and half smashed

    So here it was shortly after:

    As if that wasn’t enough torture for the week, while casting the concrete I wear rubber gloves, but this time I didn’t notice the left middle glove finger tore open and as I was moving my hands around the rubber tub mixing, the fingernail caught right up against a small bit of hardened concrete and broke a small piece of nail off.

    Just lovely, now both middle fingers are messed up for now!

    Hopefully next weekend I can get back to the Butterfly child/Mulcaster building model, I’ve not worked on it for a while and need to finish it, but right now the thought of having these two fingers in gritty wet clay is not a good idea.