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Vulcanizing Rubber at Low Temperatures


#1

I produce a significant number of Molds every year most of which are
Vulcanized Rubber. On occasion, I use RTV compounds, usually because
of the temperature limits associated with the Master; Plexiglas, Wax,
Alloys that cannot withstand 310 f, Rubberized Toy Models, etc…
Being a impulsive individual and one who wants quick turnaround, I
really don’t like the time delays associated with the curing of the
RTV type products.

Several months ago I ran across a thread here on the forum from Jul
10 2006 where Michael from Castaldo offered some samples of their Wax
Viscosity Reducer. Since I had that problem, I called and chatted
with Michael about the offer. He asked me what other challenges I was
facing and I told him the story outlined above.

Making a long story short, when he sent me the Wax Additive he
included a sample of the Castaldo VLT (Very Low Temperature) Rubber.
Not wanting to waste it, I put it on the shelf until last weekend.
The results were GREAT. I had a rubberized toy (small pig) that a
friend of my wanted me to make a mold of the head and mount it on a
ring shank to ultimately produce a Sterling Ring for her. The process
that would have normally taken me 3 days to do with RTV was
accomplished in 24 hours start to finish.

Although I won’t use nearly as much of it as I do the standard
products, my hats off to Michael for removing yet another of my
obstacles. RLW (caster at ix dot netcom dot com)

USUAL DISCLAIMERS ASSOCIATED WITH NO CONNECTION WITH THE
MANUFACTURER ONLY A SATISFIED CUSTOMER


#2

Ron,

I read your experience with the VLT from Castaldo, however I while
using this particular product seems to always have problems at the
end. I use this rubber to produce moulds from purple resin out puts
(viper) of my CAD designs. I religiously follow the instructions,
but some thing seems to go wrong and the result one lump of half done
rubber mold and the resin master spoilt. If some one can explain
step by step the process I will thank him/her for saving my time and
energy,and almost giving up on a good product.

Khushroo


#3

Hello,

I have found that you must allow your vulcaniser time to stabilize
at the correct temperature for some time. Then allow the correct
amount of time for the mould to vulcanise. This time may take some
experimenting, just try it with a blank mould.

Des


#4

Have you ever tried another mold rubber that vulcanizes at a low
temp in ten minutes with zero shrinkage? I have been using products
from Zero-D in Akron, OH for years and have found their mold rubber
to be excellent, and their injection wax too.

If you cannot get your product to work, you should try the low temp
stuff from Zero D. I am not familiar the rubber you are using with
the SLA parts, but if you contact Bill at Zero D, I bet he could help
you.

I am not affiliated with them, I just think they are a great company
and they have great service and products.

I believe they have a website, zerodproducts.com

Good luck!

Sara

Sara D. Commers
Studio C Designs
C&L Gems LLC
6005 Wayzata Blvd. Suite 100
St. Louis Park, MN 55416


#5

Khushroo,

I use this rubber to produce moulds from purple resin out puts
(viper) of my CAD designs. I religiously follow the instructions,
but some thing seems to go wrong and the result one lump of half
done rubber mold and the resin master spoilt. If some one can
explain step by step the process I will thank him/her for saving my
time and energy,and almost giving up on a good product. 

Re your message of Tue 1/23/2007 6:18 AM

Sorry, I haven’t used the resin your referring to, only the white
resin output from Stereo Lithography.

I went back to the Castaldo WebSite to try and find a clue, No Joy.
However it did raise the question regarding the use of Clean Mold
Frames and other contaminants. It appears that it is not forgiving
when it comes to mixing with other types of rubber. As I recall, the
ones that I did I followed the instructions meticulously since I try
for repeatable results and it’s just part of the ritual.

So having said that, I picked up the phone and called Mr. Knight at
Castaldo to give him a heads up to your message in case he missed
it. I believe that he monitors the forum, again, No Joy. He is on
Vacation for a couple of weeks and no one else could answer the
question.

I did leave a message for him to check the forum when he returns.

BTW if you would like to contact me offline, I’d be more that happy
to try and experiment with your resin if you have something you can
send.

Regards Caster (Ron Wade)
REPLY TO – caster at ix dot netcom dot com


#6

Sara

Have you ever tried another mold rubber...(clip)... you should try
the low temp stuff from Zero D....(clip)... Bill at Zero D, I bet
he could help you. 

I agree with you, and have used their products. I keep a stock of
them on the shelf for when I really need control for shrinkage or for
weight control of an object. And, I agree that Bill Mull would be
delighted to speak on the subject or perhaps provide a sample to see
if it will solve the problem of “purple”.

There is no doubt in my mind that when I’m looking for absolute
quality control from a product, the need to have predictable
shrinkage results, when I don’t have time for anything to go wrong
I’ll reach for Bill’s product line.

Only one caveat, and it is an industry problem not a Zero-D problem.
I find it impossible to buy the product locally here in the Dallas
area. I have mentioned it several times to the suppliers that I deal
with and they are more than helpful if I want to special order it.

I wish there was some way that we (orchidians) could have more
influence with our suppliers to extend their inventory beyond the
standard offerings that have been available for years. If I have
something special ordered or I order it direct, I don’t get the
benefit of price breaks that my suppliers can attain.

Thanks Sara for bringing another GREAT product to the forefront.

USUAL DISCLAIMERS ASSOCIATED WITH NO CONNECTION WITH THE
MANUFACTURER ONLY A SATISFIED CUSTOMER

Regards Caster (Ron Wade)


#7

Thank you Sara for your very kind comments re our mold rubbers.

Please permit me to point out that Sara makes reference to our LS250
heat cure silicone. This product, introduced a few years ago,
actually cures in only ten minutes at 250F. The really outstanding
trait, and the one of which we are most proud, is that it does not
shrink.

As far as I know, LS250 is the only heat cure rubber of any kind,
that does not shrink. There are no special preparations required,
just cure at 250F (or higher if you wish).

For more please give me a call at 440-942-1150 or
800-382-3271.

Regards,

Bill Mull
Zero-D Products, Inc.
http://www.zerodproducts.com


#8
Only one caveat, and it is an industry problem not a Zero-D
problem. I find it impossible to buy the product locally here in
the Dallas area. I have mentioned it several times to the suppliers
that I deal with and they are more than helpful if I want to
special order it. 

It is easy enough to order directly from Zero-D. And someone carries
at least one of their products – is it Gesswein? I’m away from home
and can’t look it up at the moment.

I love the 4X Gold for platinum. Fabulous.

Elaine


#9

Kushroo, your problem is not with your mold rubber. Your problem is
with the Viper resin. Viper resin is not compatible with the low
temperature cure silicones.

If you must continue to use Viper, contact Zero-D Products, Inc. for
one of our Silicone RTVs. These can be cured in one hour, or over
night–your choice.

Best wishes,

Bill Mull
Zero-D Products, Inc.
800-382-3271 or 440-942-1150
http://www.zerodproducts.com


#10

Dear Kushroo:

There are a number of heat cure silicones that work very well with
all RP resins, except for 3D Systems resins. Zero-D, Castaldo and
Nicem all have good products. The problem you have is that the
Invision 3D Systems resins do not work with the heat cure silicones.
I
had to change to Silicone RTV and have never looked back. Contact
Zero-D for their Akron RTV-RP, which is clear and very strong.

If you get on the phone with Zero-D, ask about their NO SHRINK ten
minute cure silicone. It is amazing. It does not just make a claim.
It
actually does not shrink and the ten minute cure blows all others
away! Pretty refreshing to find a product that actually does what the
literature claims.

Craig


#11

Kushroo, you need to use Silicone RTV with 3D Systems models. I use
Zero-D Lovis (aqua color) and Akron RTV clear, also from Zero-D. I
can use VLT or LSLT-160 with the other resins.

Lori