If you are a sculptor in any medium, one of the most often asked
questions you get, other than “Is it really art?” will probably be “What’s it
made from?” I got a delivery of goodies today so I thought I’d give you a
little run down of what I use most of. Since moving to Australia I have been
using a majority of Barnes products for moulds and casting. I often buy from Adelaide
Moulding and Casting supplies mainly because their service is fantastic but also,
even though it needs shipping I find their prices competitive. They also stock
a diverse range so depending on weight, I can throw in a little something extra.
No, I don’t work for them or Barnes. I just dig ‘em.
The Ultrasil Pro is a condensation-curing silicone. It has a shore
of about 25 with excellent flow and detail reproduction. It has a 20 minute pot
life and cures in around 7 hours or so. I always leave it over night anyway so
you know it’s a guaranteed start the next morning. So far, even during our
Melbourne winters I’ve had minimal temperature retardation issues, although during
the height of summer my work time decreases dramatically. Most of my moulds
these days are matrix or jacket moulds which I find suits Ultrasil Pro
perfectly. It’s very forgiving with undercuts and its high tear resistance and
low shore is perfect for a first time dodgy jacket. Remember to always store
your moulds away from sunlight and heat and you’ll find Ultrasil moulds will
outlast their need.
I also received some dental Alginate which I actually use quite
often. It’s very handy for a quick reproduction if you have a simple shaped but
delicate positive. As far as I know most alginates are pretty much the same
thing so follow your instructions and you’ll be good to go. Obliviously the
water in your Alginate mould won’t play nice with any resins so your new master
will have to be plaster.
For mould jackets I’ve used plaster and these days fiberglass (not
pictured). The draw backs with plaster is if you develop a crack, that’s it.
Fiberglass is a little more forgiving but a whole other skillset. I encourage
anyone looking to get into fiberglass to do so. It is quite a learning curve
but well worth it.
I’ve used a variety of resins over the years. Early on in my
casting I used a slow cure polyester resin. The long pot life is great if you
are little nervous but also handy if you have a mould with a slow pour. It’s
also good for casting with internal armatures or for casts that might be
thinner than normal. Both instances can promote bubbles so the slow curing
gives you plenty of time to work those nasties out. Ideally a pressure pot
would be used but if you don’t have one you still have a shot with slow a cure.
These days I’m using Easycast Polyurethane. It’s equal parts by weight, has a
60 second pot life and 2-2.5 minute work time. The biggest advantage to Polyurethane
is it has less smell and toxins than polyester resin but I’ve not noticed any
difference in detail. Easycast also takes colour and metals very well if that’s
your thing and I find it to be far more durable than polyester. This is an extremely
fast curing resin and I only use it on particular sculpts. I would encourage
anyone to only use this on a simple two part or open box mould if you’re a beginner.
You’d be surprised how fast a minute can disappear when you are pouring.
I also use a lot of plaster for
casting. Again, like the alginate it’s a relatively simple procedure but like
resin, it is an exothermal reaction which will speed up the setting over time.
It will seem to be setting slowly but then just kick. This is only an issue for
slush casting so keep your eye on it; most plasters set within 10 minutes. Most
importantly, DO NOT use plaster for mould making on the human body unless you
know what you are doing. Google “Schoolgirl, 16, lost eight fingers in plaster
of Paris accident during art lesson” if you don’t believe me.
So that’s this weeks episode of Bazza’s
product bias, next week we’ll cover political parties and cell phones. In the meantime,
if you have any questions, please try and find the TDS (technical data sheet)
for the products you are thinking about buying (they’re always published
online) and read them over and over. Chances are whatever you’re wondering will
be in them and for safety, have your TDS with you while you are casting. If you
can’t find the products I’ve mentioned stocked near you, I’m sure you’ll be
able to track them down by their properties, shore strength and pot life etc.
Like most things the right tool for the right job applies to all casting and
moulding materials. Trial and error is sometimes the only way to figure that
out but if you want to learn more about casting or mould making there is a wealth
of material on YouTube. If you have any other questions please feel free to shout