|  | | | Mould Making and Casting Supplies | | | Maintained by: | | A one stop shop for all your mould making and casting supplies. Perfect for modellers, casters,mouldmakers, fibrehands and fibrous plasterers! RTV Silicone Rubber, Latex, Plaster, Timber Lath, Jute Hessian, Specialist Tools, Sculpture Clay, all at exceptional prices and direct from stock. UK Based. | |
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 | | Pay promptly for same day despatch. Items purchased after midday cannot be guaranteed to be despatched the same day! All items are sent via overnight courier with the exception of some remote postcodes and offshore. We reserve the right to add additional postage where applicable, however Citylink offer the largest range of non surchargeable postcodes. Our free delivery option applies ONLY to Citylink zone ONE. Further details are on the Citylink website! If in doubt, ask prior to purchase! |
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Mould
Making & Casting Supplies - About Our RTV Mould Making Silicone
Systems
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What is
Shore A Hardness?
Essentially this is an international adopted scale which defines
the hardness of a product be it plastic or rubber and many other
things too! As a general rule the higher the number the harder the
RTV Silicone will be.
It will be more
durable it is and its tear strength will usually increase. There
are of course downsides to increasing Shore A which include reducing
elongation to break (stretchiness in Layman speak).
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How safe
are Condensation Cure RTV Silicone Systems?
In a single word, "Very". The RTV SIlicone Base is nigh
harmless and non hazardous, don't get it in your eyes or on your
clothes though. Only the catalyst of our systems is hazardous and
is flammable due to alcohol content.
The catalyst,
either fast or slow, contains Tin, an accumulative poison like lead.
So wear gloves and definitely dont drink it (however nice it may
smell!). keep it out of reach of minors.
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So I have
a former with deep undercuts, which Silicone?
Deep undercuts present issues during demould. Putting it simply
they will hang on to your cast like trying to pull a triangle through
a round hole! Its just not going to happen!So a more flexible RTV
Silicone will allow easier withdrawal of a deeply undercut piece.
However with
a benefit there always a drawback. The softer the RTV Silicone the
more likely it will sag or slump, deforming your cast! So there
is a fine balance to judge and mainly experience will tell you what
you may get away with.
Latex demoulds
from the deepest of undercuts but isnt compatible with all casting
medias. Therefore sometimes you just have to make a sectional or
split mould to prevent slump but give easier release.
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What
are Addition Cure RTV Silicones?
These are two part systems where part A looks like rubber and so
does part B usually. There is no "catalyst" just 2 parts
to be mixed together often in 1:1 by weight. These addition cures
are usually skin safe as the catalyst part is Platinum and not Tin
which is inert to the human body.
There
are two types of these, which we will stock shortly. Regular addition
cure for mouldmaking and Food Safe which can be used in baking and
making sugar candies, chocolates, muffins and more.
Never
use a Condensation RTV (Tin Cure) for life casting, or to make food
shapes, the Tin is very harmful and should be respected. Ask yourself,
would you serve dinner on a Lead Plate?
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I have
a simple shape, no undercuts, now which one?
Hard will give good durability but dont be in a hurry to go with
hard. If you rough handle it may well split and then the mould is
destined for the refuse
Consider trying
the medium grade and move onto hard if you find durability an issue.
Some media like polyesters and polyurethanes are aggressive on RTV's
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Whats
the RTV stand for?
RTV means Room Temperature Vulcanizing. In other words the reaction
can occur at room temperature or thereabouts, not in an oven or elevated
temperature. Bear in mind that in the cold, cure (or hardening) will
take longer, do not be impatient and demould too soon, you will ruin
your mould. Better to wait and be sure if you are operating in the
cold or make a mistake with catalyst. |
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Whats
the best all rounder?
Our Medium grade is used by 9/10 of our customers, has good durability
and releases well from undercuts. Its popular in sectional or split
moulds too and it definitely a good place to start. Its also our
suppliers biggest seller which must tell you something!
If you are new
to RTV Silicone and really dont know where to start, go for the
medium grade and make some smaller moulds and build knowledge and
confidence!
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OK
I Picked my RTV Silicone Hardness - Which Catalyst: Fast or Slow!
Fast is the choice for smaller moulds or the seasoned pro. Its fine
in the winter but in the summer can catch out even the most experienced,
with potlife (useable time) dropping to as little as 5 minutes!
You can demould and cast same day, though if using polyesters and
PU's we recommend a post cure of 48 hours.
Slow
is good in warmer temperatures and for the novice. It does produce
a better RTV Silicone Mould allowing the rubber to cure slower it
will give better durability. However its an overnight curing system,
but as we said be patient!
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Thanks
for taking the time to read this section on our RTV Silicone Systems.
We appreciate your custom and look forward to not only receiving
you first order but any subsequent orders you place. You will get
the same level of service whether you are making a one off purchase
or become a regular customer! All information is supplied in good
faith and for guidance purposes. No responsibility or liability
for loss or personal injury can be accepted. The products are supplied
as fit for the purpose intended.
We
are customer focussed and seek to maintain a 100% feedback score.
Visit our website for more information on mould making with our
products and watch out for the new casting, filler use, troubleshooting
and public forum sections coming soon!
TOMPS
Online Management Team
www.tomps.com
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