Cutting Up My Sculpture For Mold Making

[Hyn Patty]

Porthos is a sculpture I did in 'traditional' 1/9th scale and completed in late 2021.  He depicts an American Percheron or other American breed draft  horse with his head and neck turned around to look behind him.  He stands with one back leg cocked.  I first had him cast in a limited edition resin but also 3D scanned so I could reduce his scale and produce him in smaller sizes in limited edition resin as well. 

Shown here is a full 1/9th scale hollow cast resin of my original sculpture that I have cut up to prep for mold making.  Normally equine pieces in the USA are molded so that the horse is cast whole and in one piece.  But this limits the positions the horse can be in and makes for some very large, very heavy molds even before slip is poured into them.  That is suitable for earthenware but not as practical for casting porcelain or fine bone china which can not abide any bending of the wet clay when demolding.  So I have cut him up and will finish prepping him to cast in pieces in my choice of earthenware, porcelain, or fine bone china and then assembled in my studio before bisque firing. 

I will also be cutting up and producing a 'mini' version of my sculpture, probably 3D printed and mirrored to face the other direction.  Some pieces will be individually claybody customized with various manes and tails, or have additional show ribbons added.  Some may be on bases and others without.  Many pieces in the limited editions will be custom glazed by myself and sold at public auction when completed.   Lots of photos in my Hyn Patty LLC gallery page of examples of pieces I have completed in the past, some sculpted by myself, others I've merely custom glazed but were sculpted by other artists.

[Hyn Patty]

I used an ultra thin jeweler's saw to cut these pieces up.  Now is the finicky part of prep to make sure each piece fits back together as precisely as possible before I proceed.  A good friend reminds me that it is a better idea to take the leap into making a poured rubber mold and casting a rubber master.  A rubber master can be cut up using a sharp blade and therefor suffer no material loss.  It is also much easier to make very precise molds, and make production replacement molds, if you have a rubber master of the sculpture to work from.  This method shown above utilizing a rigid original that is cut up will also work but isn't as practical for production molds where you need to be able to make a lot of casts.

This version of my Porthos isn't the one I really want to be producing.  It is my new Pasture Porthos I really want to get into production.  So this is a screw around project to knock some rust off.   I took a decade off from my studio years ago when I suffered from Lyme Disease and then a bad motorcycle accident that left me unable to walk.   Surgery and lots of PT eventually got me back on my feet but my art studio was closed for a decade because of it.

Even so, I can (and have in the past) made useful molds this way for very small editions on a tight budget.  My Wee Bairn sculpture is a good example of that where I was only aiming for a 10 piece edition. 

Casting rubbers are pretty expensive and you will need a lot to make block molds and pour rubber masters.  Several hundred dollars worth of rubber at a time which is easy to screw up and waste.  So starting out practicing making small, simply shaped rubber masters.  I am currently working on making a rubber master for a medallion to brush up on rubber mold making skills I haven't used in more than a decade.  By comparison, brush on or thinly poured rubbers used to make layer waste molds are far easier to work with - but won't get this kind of work done.

[LeeU]

I just checked out your website--amazing work!! I can not even fathom the patience and focus you must have to do such detailed and precise images, whether paintings (love Mac/dog & bear w/water!) or the fine ceramics horses! 

[Hyn Patty]

On 8/8/2023 at 9:13 PM, LeeU said:

I just checked out your website--amazing work!! I can not even fathom the patience and focus you must have to do such detailed and precise images, whether paintings (love Mac/dog & bear w/water!) or the fine ceramics horses! 

Kind words, thank you.  It's taken me most of a life time to get where I am, having started my art studio and equine art in general way back in 1976.  I didn't really start sculpting horses until around 1984, and my first attempts at mold making also in High School, before I went onto the Savannah College of Art & Design where sculpture wasn't available as a major, but I did eat up all the sculpting and mold making classes that were available (only two if I recall back then, alas).  So I have had to learn most of what I know about sculpting and mold making on my own, scouring the internet (once it became available to me in the early 90's) through a great deal of trial and error.  I did however come away from college with both a BFA in Illustration and a MFA in  Painting at least, with double minors in jewelry and art history.  Well worth the effort!

Edited August 10, 2023 by Hyn Patty

[Hyn Patty]

Despite the advantages of a rubber master casting of my sculptures, after some debate with myself I have decided to stick to using my resin and oil clay originals to make my rubber masters for casting plaster production slip casting molds.  It's what I am used to, and getting good rubber masters cast of my sculptures is rife with challenges that tend to waste more rubber than I like.  So, I am not going to worry too much about the extremely tiny amounts of resin lost in sawing the pieces apart.  I don't use a hacksaw with a thick blade, but rather I use nearly hair thin jeweler's blades set into coping saws that allow me to make fairly precise, ultra thin cuts that are almost as clean as cutting up a rubber master. 

It can be very difficult, even with a pressure pot, to get good rubber masters cast due to thin legs and other narrow parts.  In due time I'll likely move onto doing it that way - but for now my less common method works well enough for my purposes and saves me a little time and expense in the process.  Do whichever works best for you!