Pouring Boxes - two versions

[Jeff Longtin]

I was recently asked about a pouring box for mold making. Here are two versions I use in the studio.  The image with the bulbous object is my main pouring box. The pieces are 3/4" plywood cut into 5"x15" boards. I then screwed 1"x1" strips onto the ends which provide a lip for the small "C" clamps. Very quick and easy to assemble a box in any dimension.

The second image shows another box variation that I use often for flat castings. The sides of the box are 2"x2" pieces of pine. (In his case I also used some 1"x2" strips.) The 2x2 pieces are labeled as "turning blanks" and come in a variety of wood types.  (Woodworkers use them to make stairway balusters.) Because they are square and stocky they don't need much bracing other than a little clay at their base. 

The mold on the left I free formed and did not use the box to limit the plaster. (I shaped it by hand.) The mold on the right I filled the box with plaster and then ran a straight edge along the tops of the wood pieces which resulted in a mold that was evenly thick. 

 

[Min]

Do you ever use roof flashing for casting of simple one piece molds? (just curious)

[Jeff Longtin]

Min - Rather than use roof flashing I use thin plastic sheeting. (I was working at a large corporation, years ago, and they were transiting away from thin plastic sheets, to protect desk tops, to a formica desk top, so I collected lots of thin plastic sheets.)

While the plastic sheets are nice, when I mold round forms, (as opposed to a square pouring box) I sometimes forget that they need to be held down, at the bottom of the shape, as well as strapped together, at the top of the shape, to prevent the whole thing lifting up. (and covering my shoes and pants with a thin layer of plaster splatter.)

[Chilly]

I have similar, but have also used tupperware boxes, cardboard boxes lined with large plastic bin bags, and fruit boxes, also lined.  Anything that is larger "enough".

 

Edited June 17 by Chilly
typo

[Hyn Patty]

I use ALL of the above at various times and for really little mold boxes I've even tried using Legos.  But I decided Legos were too slow, and too much a pain to clean up and reuse again compared to sealed wood or plastic mold boards.  I too also use plastic containers, or if the molds are small I've also been known to cut up and make mold boxes out of foam core (soaped) or thick plexiglass sheet I cut to the sizes I like.  Whatever works!  If I'm just making a quickie waste mold that' not very big I also am a fan of using slabs of oil clay to build my walls.    Just stick the clay down on my formica countertop and make whatever custom shapes I want pretty quickly.  I can reuse the oil clay over and over and just toss it into one of my crock pots to melt it back down later.

Here is an example of a simple mold I needed fast.  I made the base in oil clay and then clayed up the walls around it.  Once I was sure it was all sealed down, I poured the plaster.  Great for fast one or two part molds that I don't need a 'box' form for the completed piece.  If I'm making a production mold I will cast from a lot though I'm more apt to take the time to use my mold boxes and use more plaster.  I also make rubber masters for those so I can pour as many plaster production molds as I want later.

I find it's very easy to trim and smooth the plaster afterwards while it's still wet and not wholly cured, but hard enough to remold it.  So if I want smoothed more regular shapes I can achieve that easily even if I clayed up an odd shape to start.   Helps make sure my pieces form a nice whole without sharp edges.

Edited June 13 by Hyn Patty