Silicones

RTV TOMPS VALUE Silicone Mould Making Rubber (version 2)


1.Calculate the amount of rubber you need! The next 3 steps tell you how! Silicone is about 1.27kg per litre.
2. Drop your item into a graduated beaker/pint jug etc. Fill with water to a set point, say 500ml. Remove your piece. The difference in the water level is the volume of your former.
3. Next calculate the volume of your box that you will fix your former in and pour into. Again calculate in litres
4. The difference between the two is the volume of silicone you will need. Multiply by 1.27 and this will give you kilos needed.
5. You may wish to add 5-10% for contingency. Then weigh it out into a mixing pot. Don't forget to zero the scales for the mixing pot!
6. Then calculate catalyst needed. The ratio is 3% . From a weight perspective that's 30g cat to 1kg silicone base. Divide grams by 100 and multiply by three.
7. Next add the catalyst to the base. START YOUR TIMER NOW!
8. Homogenise gently until the colour is solid. DO NOT WHISK!!!!!!
9. Make sure you get all of the base mixed with catalyst. Scrape the edges and bottom of the pot with your mixing stick.
10. For total mix move the mix from one pot to another and remix.
11. Allow to stand for a few moments (if using slow catalyst, with fast there will not be time) this allows air to release
12. Pour SLOWLY into the lowest corner of your box allowing it to flow up and over the former.
13. DO NOT TIP ONTO FORMER you will most like create air pockets.
14. Allow to cure - see the data below for cure times according to catalyst
15. Demould carefully and slowly, being careful with undercuts etc.
16. A slow catalyst that gives a potlife of approximately 30-45mins, a tack free time 4-6 hrs, a demould time of 10hrs and a 95% cure time 14-24hrs.
17. A fast catalyst that gives a pot life of approximately 10-20 mins, tack free time 0.5-1 hrs, demould time 3hrs, 95% cure time 5-8hrs
18. If its cold the cure will take longer and the potlife will be longer. The reverse applies for warm conditions. If in doubt run a sample.

 

RTV Silicone Mould Making Rubber (ACC Silicones)


1.Calculate the amount of rubber you need! The next 3 steps tell you how! Silicone is about 1.27kg per litre.
2. Drop your item into a graduated beaker/pint jug etc. Fill with water to a set point, say 500ml. Remove your piece. The difference in the water level is the volume of your former.
3. Next calculate the volume of your box that you will fix your former in and pour into. Again calculate in litres
4. The difference between the two is the volume of silicone you will need. Multiply by 1.27 and this will give you kilos needed.
5. You may wish to add 5-10% for contingency. Then weigh it out into a mixing pot. Don't forget to zero the scales for the mixing pot!
6. Then calculate catalyst needed. The ratio is 20:1. From a weight perspective that's 50g cat to 1kg silicone base.
7. Next add the catalyst to the base. START YOUR TIMER NOW!
8. Homogenise gently until the colour is solid. DO NOT WHISK!!!!!!
9. Make sure you get all of the base mixed with catalyst. Scrape the edges and bottom of the pot with your mixing stick.
10. For total mix move the mix from one pot to another and remix.
11. Allow to stand for a few moments (if using slow catalyst, with fast there will not be time) this allows air to release
12. Pour SLOWLY into the lowest corner of your box allowing it to flow up and over the former.
13. DO NOT TIP ONTO FORMER you will most like create air pockets.
14. Allow to cure - see the data below for cure times according to catalyst
15. Demould carefully and slowly, being careful with undercuts etc.
16. A slow catalyst that gives a potlife of approximately 30-45mins, a tack free time 4-6 hrs, a demould time of 10hrs and a 95% cure time 14-24hrs.
17. A fast catalyst that gives a pot life of approximately 5-15 mins, tack free time 0.5-1 hrs, demould time 3hrs, 95% cure time 5-8hrs
18. If its cold the cure will take longer and the potlife will be longer. The reverse applies for warm conditions. If in doubt run a sample.


Heat Resistant RTV Silicone


1.Before you start this product needs uber accurate measuring facilities! 0.1g increment scales are a must!
2.The kit arrives with exactly the right mix ratios in the pots
3.Follow the same mixing guides as normal RTV EXCEPT the catalyst addition ratio is 100:10 (100g base to 1g catalyst)
4.Allow to cure for 24 hrs
5.Demould and place rubber in oven at low heat to start conditioning it for heat use
6.Start at 50 Celsius and increase every 1-2 hrs by 50 degrees
7.Max temp 200 degrees for an hour
8.You may then use low melt alloys, pewter etc with pouring temps up to 300 Celsius and melting points up to 250
9.Rubber is designed for use at maxim 250 Celsius with a short spike to 300 Celsius

 

Viscolo 13,22,33,45 & 50 Addition Cure 1:1 Silicone



1. This RTV Silicone may be measure via volume or weight since its SG is balanced
2. Calculate the volume of rubber you need using a similar method to regular rtv above
3. This volume in cubic centimetres also matches the weight of rubber you need eg 500cc=500g
5. Half the weight you have calculated, eg 250g and charge a clean mxing pot with that weight of Part A (or indeed the volume!)
6. Reset the scales and add the other half ie 250g of catalyst, or top up to the desired volume
7. Ensure measurement accuracy is within 5%
8. Mix briskly until uniform in colour, allow to stand for 1 minute for air release (or degass in chamber now)
9. Pour into mould case or cavity, pour slowly and in the lowest corner, trying not to trap air
10. Allow to fully cure and demould (refer to datasheet for times)

 

TOMPS TIPS
--If using silicone, ensure your measurements are as accurate as possible
--Do NOT use volumetric measuring except for Viscolo22 on any silicone, its not accurate enough!
--Any areas not cured on demould indicate insufficient cure time, mixing or catalyst
--NEVER use shellac to seal a former, it reacts with silicone and ruins the surface
--NEVER use latex gloves when using Viscolo 22, it inhibits the cure
--Use caution when choosing a former for Viscolo 22, plasticine may inhibit cure - seal with a varnish to help block the inhibitors if needed
--Onion and Garlic juices and Plasticisers in general can inhibit Viscolo 22