Downloads (2)

Safety Datasheet (SDS)395 KB
Technical Datasheet (TDS)282 KB

Specification

Product Data
ColourClear
Chemistry / MaterialRTV Silicone Rubber
Viscosity50000mPa.s
Pot Life (Typical)30mins
Initial Cure Time24Hrs
Cured Mechanical Properties
Max Service Temp250°C
Hardness40 (Flexible)Shore A
FlexibilityFlexible
General Properties
Gross Weight0.581kg

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AS40 Addition Cure Silicone Rubber

AS40 is a professional quality addition cure (also known as platinum cure) RTV silicone rubber suitable for the production of silicone moulds and silicone mouldings/components. It cures translucent to a 40 shore A (medium flexible) hardness. AS40 requires degassing for best results.

Sold as a kit (silicone and catalyst). Available to buy online in 500g, 1kg, 5kg and 27.5kg kits.


PRODUCT VERSIONS

Kit Size

AVAILABILITY:More than 10 availablefor immediate shipping


PRICE
£12.50ex. VAT
(£25.00 /KG)
More than 10 availablefor immediate shipping
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EACH
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AS40 is a high quality 'addition cure' (platinum cure) silicone rubber for more demanding mould making applications.

Addition cure rtv silicone should be used in applications where very accurate dimensional reproduction of an original part is required such as in rapid prototyping, where higher temperature tolerance is required or where the maximum number of repetitive releases will be possible.

Our addition cure silicone has been chosen for its excellent dimension reproduction; it is incredibly low shrink and therefore can be used to make a mould for prototype parts that interconnect (like a nut and bolt) to engineering tolerances. It has excellent styrene and polyurethane resistance and a high tear strength.

Suggested Uses

Use our AS40 Addition Cure Rubber to produce accurate moulds of complicated parts, precisely reproducing the dimensions of the original part. Completed silicone moulds can be used for repetitive casting applications, ceramics, vacuum casting and general mould making.

Advantages

  • Very accurate reproduction of dimensions (very low shrinkage)
  • Translucent
  • High tear strength
  • Styrene and PU resistant

How to Buy

Easy Composites' AS40 Addition Cure Silicone Rubber is available in four different pack sizes: 0.5kg, 1kg, 5kg and 27.5kg. All packs include the correct ratio of silicone rubber and catalyst (hardener). Please choose the pack size you want from the drop-down list.

Further Information

Mixing Ratio

100 p.b.w. Addition Cure Silicone Rubber

10 p.b.w. Addition Cure Silicone Rubber Catalyst

Brief Description of Typical Use


A part to be copied is positioned within a 'setup box' which will contain the silicone rubber whilst it cures.

The silicone rubber is thoroughly mixed with its catalyst at the correct ratio and then placed in a de-gassing chamber to remove any air trapped within the mixed silicone. If a de-gassing chamber is not available it might be possible to satisfactorily de-gas the silicone using the 'stretch pour' method (see accompanying datasheet for more info).

Once the silicone has been de-gassed it is carefully poured into a single place at the bottom of the setup box (to avoid accidental aeration) and once the setup box is full of rubber the whole box is placed in the vacuum chamber to de-gas again. The silicone will cure at room temperature in 24hrs or can be cured at an elevated temperature to hasten then cure (see accompanying datasheet).

Compatibility Information - Dos and Don'ts

Although by no means an exhaustive list, the mould materials, pigments and additives listed below have all been tested and are known to work well with AS40 Addition Cure Silicone.

Compatible Moulds

  • Almost all Plastic moulds*
  • Metal moulds
  • Addition Cure Silicone moulds with a release agent

Compatible Pigments

  • RTV Silicone Colour Pigment (for vivid opaque colours)
  • Translucent Tinting Pigment (for less vivid opaque colours)

Compatible Fillers

  • Thixotropic Additive for Addition Cure Silicone

* Certain materials can inhibit the cure of Addition Cure silicones. Please check the list in the TDS if you are unsure of compatibility.

Key Processing Information

Ease of Use

Suitable for professional and hobby use (follow SDS advice).

Odour

AS40 is almost odourless.

Safety Precautions

Wear gloves and goggles and work in a well ventilated area. Always read the SDS before use.

Ambient Conditions

Can be used from 10 to 30°C although pot-life and cure time will be affected significantly.

Degassing

Recommended for best results. Stretch pour method best if degassing unavailable.

Mix Ratio

Mix silicone and Catalyst 100:10 by weight. Use digital scales.

Mixing

Mix thoroughly by hand for at around 2 minutes.

Pot-Life

30 Minutes. Be sure to pour your casting(s) before this time.

Cure Time/Demould

Demould Time 24 Hours @ 25°C

AS40 is a high quality 'addition cure' (platinum cure) silicone rubber for more demanding mould making applications.

Addition cure rtv silicone should be used in applications where very accurate dimensional reproduction of an original part is required such as in rapid prototyping, where higher temperature tolerance is required or where the maximum number of repetitive releases will be possible.

Our addition cure silicone has been chosen for its excellent dimension reproduction; it is incredibly low shrink and therefore can be used to make a mould for prototype parts that interconnect (like a nut and bolt) to engineering tolerances. It has excellent styrene and polyurethane resistance and a high tear strength.

Suggested Uses

Use our AS40 Addition Cure Rubber to produce accurate moulds of complicated parts, precisely reproducing the dimensions of the original part. Completed silicone moulds can be used for repetitive casting applications, ceramics, vacuum casting and general mould making.

Advantages

  • Very accurate reproduction of dimensions (very low shrinkage)
  • Translucent
  • High tear strength
  • Styrene and PU resistant

How to Buy

Easy Composites' AS40 Addition Cure Silicone Rubber is available in four different pack sizes: 0.5kg, 1kg, 5kg and 27.5kg. All packs include the correct ratio of silicone rubber and catalyst (hardener). Please choose the pack size you want from the drop-down list.

Further Information

Mixing Ratio

100 p.b.w. Addition Cure Silicone Rubber

10 p.b.w. Addition Cure Silicone Rubber Catalyst

Brief Description of Typical Use


A part to be copied is positioned within a 'setup box' which will contain the silicone rubber whilst it cures.

The silicone rubber is thoroughly mixed with its catalyst at the correct ratio and then placed in a de-gassing chamber to remove any air trapped within the mixed silicone. If a de-gassing chamber is not available it might be possible to satisfactorily de-gas the silicone using the 'stretch pour' method (see accompanying datasheet for more info).

Once the silicone has been de-gassed it is carefully poured into a single place at the bottom of the setup box (to avoid accidental aeration) and once the setup box is full of rubber the whole box is placed in the vacuum chamber to de-gas again. The silicone will cure at room temperature in 24hrs or can be cured at an elevated temperature to hasten then cure (see accompanying datasheet).

Compatibility Information - Dos and Don'ts

Although by no means an exhaustive list, the mould materials, pigments and additives listed below have all been tested and are known to work well with AS40 Addition Cure Silicone.

Compatible Moulds

  • Almost all Plastic moulds*
  • Metal moulds
  • Addition Cure Silicone moulds with a release agent

Compatible Pigments

  • RTV Silicone Colour Pigment (for vivid opaque colours)
  • Translucent Tinting Pigment (for less vivid opaque colours)

Compatible Fillers

  • Thixotropic Additive for Addition Cure Silicone

* Certain materials can inhibit the cure of Addition Cure silicones. Please check the list in the TDS if you are unsure of compatibility.

Key Processing Information

Ease of Use

Suitable for professional and hobby use (follow SDS advice).

Odour

AS40 is almost odourless.

Safety Precautions

Wear gloves and goggles and work in a well ventilated area. Always read the SDS before use.

Ambient Conditions

Can be used from 10 to 30°C although pot-life and cure time will be affected significantly.

Degassing

Recommended for best results. Stretch pour method best if degassing unavailable.

Mix Ratio

Mix silicone and Catalyst 100:10 by weight. Use digital scales.

Mixing

Mix thoroughly by hand for at around 2 minutes.

Pot-Life

30 Minutes. Be sure to pour your casting(s) before this time.

Cure Time/Demould

Demould Time 24 Hours @ 25°C

Downloads (2)

Safety Datasheet (SDS)395 KB
Technical Datasheet (TDS)282 KB

Specification

Product Data
ColourClear
Chemistry / MaterialRTV Silicone Rubber
Viscosity50000mPa.s
Pot Life (Typical)30mins
Initial Cure Time24Hrs
Cured Mechanical Properties
Max Service Temp250°C
Hardness40 (Flexible)Shore A
FlexibilityFlexible
General Properties
Gross Weight0.581kg
Can’t find the answer you’re looking for?Ask our technical team a question.

No, we do not have any additives that will reduce the viscosity. However, often despite the apparent high viscosity, the Silicones have very good flow properties and will flow into fine details and gaps much smaller than you would expect.

A thin smear of Vaseline (which can be thinned if necessary using methylated spirits) makes a good release agents between separate pours of RTV silicone.

Generally speaking, no, you do not need a release agent as really doesn’t stick to much at all. There are a couple of exceptions; firstly it sticks very well to itself and secondly it can stick (or at least ‘grip’) to porous materials. Porous materials and items with fragile surfaces should be sealed to prevent any sticking or damage during the moulding process. PVA, Shellac (sanding sealer) or paint/lacquer can all be used to seal the surface of porous materials. If in doubt, always test a small area first.

As long as the surface is free of dirt and contamination, then this silicone will stick to itself when you do the second pour. If the first pour of silicone has fully cured when you make the second pour then although it will bond and will become a single piece mould, the bond-line is likely to remain a weak-point.

If properly mixed and cured the cured silicone should be inert, none-reactive and none-toxic so there should be no reason why it would not be safe for skin contact however the product has not been specifically evaluated for medical use and so for commercial use in a medical application you might need to look further into whether any accreditation or independent testing is required.

The silicone itself can certainly be used on its own. When you buy the product you get the silicone and its catalyst together. Mix up as much (or as little) as you need and then pour them to create your cured rubber part. You can use the rubber to make a silicone mould (which you could then pour casting resin into) or to make rubber parts themselves (which would normally mean pouring the liquid rubber into a rigid mould).

Pretty much the only material silicone will stick to is other silicone, so a release agent is needed. A thin smear of Vaseline (which can be thinned using methylated spirits) or a spray wax called Macwax make effective release agents when you need to release silicone from silicone.

No, it’s probably not advisable. Polyester resin inhibits the cure of Addition Cure Silicone Rubbers. Older polyester patterns which have stabilised completely might be OK but certainly newer ones with fresh resin could stop the silicone from curing properly. For your application you would be better off with our Condensation Cure Silicone Rubber which has far fewer compatibility issues with cure inhibition.

Yes, absolutely, AS40 is highly suitable for use in taking moulds off existing concrete castings or objects. If the concrete is particularly coarse in texture then it might be better to use something like a mould release wax on the concrete which will smooth the surface texture; this will make it easier to separate the silicone mould from the concrete part and also ensure that the mould has a smoother surface which will help the parts that are cast into the silicone mould to release. If the concrete part already has a smooth surface then this is not necessary.

No, not using the AS40 silicone on its own, the silicone would run and pool at the bottom. However, you can add some of our Thixotropic Additive for Addition Cure Silicone Rubber to thicken it to the point where it can be brushed on a surface without running.

.....Does the silicone release toxic fumes and bad odour at this temperature in the oven?

The Addition Cure Silicone has a maximum service temperature of 250°C so should be fine at that temperature. Fully cured silicone does not give off any odour or fumes.

Moulds made from our AS40 Addition Cure silicone are suitable to be used in both degassing chambers and pressure pots.

Yes, AS40 addition cure silicone needs only the catalyst to cure and as such lack of air in a closed mould will not cause any curing issues.

Uncured spills and drips are best wiped up with a cloth. Solvents like acetone and white spirit have little effect so if there is any slight residue after cleanup then a mildly abrasive surfactant cleaner (like Cif kitchen cleaner) works well.  Alternatively, cured silicone will simply peel from almost all surfaces.

The maximum service temperature of this AS40 silicone is 250°C. 

Although some white metals have a melting point of 250°C, most are slightly over this (up to about 300°C) which would be too hot to reliably cast into this silicone.

If you degas the silicone while making the mould, then yes you should be able to see the edges of the cast and be able to tell if you have any air voids in your mould. Without degassing, you will still see the black resin, although it may not be clear enough to tell if there are some small air pockets.

The AS40 Addition Cure silicone will take a mould from a polyurethane pattern no problem. As long as the surface is smooth and non-porous then no release agent would be required. If the polyurethane you're using is quite low density (such as a PU foam) then it would be necessary to seal the pattern with something like a coat of epoxy resin like our XCR Epoxy Coating Resin.

Certainly do NOT use a polyester resin/primer to seal the pattern as polyester resins inhibit the cure of addition cure silicones.

Yes, the silicone accepts pigments very well and can be coloured using our range of liquid silicone pigments or using alternative pigments that are designed specifically for pigmenting RTV silicone.

As for 'stiffening' the silicone, it rather depends what you mean by this. If you mean increasing its shore hardness then no, this is not possible. If, instead you mean can the mould be reinforced then yes, this is possible but it's worth being aware that the reinforcement material (unless you use more of the same silicone) will not bond to the silicone, it will only mechanically hold it. A common example of this is creating a fibreglass shell to support a thin-wall silicone mould (a glove mould). If you're thinking of reinforcing the silicone with more silicone then this can be done and the AS40 will bodn to cured AS40 making it possible to add ripstop netting (or similar) along with more silicone onto the back of a cured mould to reinforce it.

This is a type of one-component silicone sealants used for a variety of uses (from window sealants to gaskets).

No, this Addition cure silicone is not 'food safe' or FDA approved silicone so it should not be used for food use. We don't carry any food-safe silicone at this time.

Our Addition Cure silicone is translucent; it's not perfectly clear but it lets plenty of light through and has no colour of its own, just a slight diffraction of the light which gives it a sort of frosty appearance. Because it is colourless it can be pigmented fantastically using our range of RTV Silicone Rubber Pigments which can be added anywhere from a tiny tint to a vivid colour. For translucent effects a pin-prick of pigment can tint the silicone to a faint red, blue, white (opal) effect with great results.

For best results, yes - we recommend vacuum degassing our Addition Cure Silicone Rubber. If you don’t have a vacuum degassing system then our CS2 Condensation Cure Silicone Rubber is lower viscosity and degasses itself quite well without the need for vacuum degassing. If you do want to use this Addition Cure silicone and no vacuum chamber is available it might still be possible to de-gas the mixed silicone adequately using the ‘stretch-pour’ method whereby the silicone is poured into the mould by means of a very small hole in the bottom of a vessel containing the mixed silicone. The vessel should be positioned at a height of more than 1m above the set-up box and allowed to pour into a corner of the set-up box in a very thin trickle.

ASK YOUR OWN QUESTION

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Customer Product Reviews for AS40 Addition Cure Silicone Rubber

2/5 Average rating
21/5/2021
|
Gary B.
|

I was a little disappointed with this silicone rubber. With both parts being clear, it is difficult to tell when it is fully mixed - I much prefer other brands that have a coloured reactive agent so you can tell when it's mixed when it's blended into a consistent colour. It also had a lot more air bubbles than other brands I've used, which made some of the moulds I made unusable, which I've never experienced before with other brands. And my final issue was that it seemed thicker and harder to pour than the brand I normally use, which made it all round difficult to use. So all in all I don't think I'd buy this again unfortunately. A pity really as other products purchased were good and I was hoping to be able to buy everything in one place to avoid multiple orders from different shops to get everything I need.

Easy Composites Response

Thanks for your feedback, we're sorry to hear of your disappointment and the issues you experienced. As you said the AS40 is thicker and can be more bubbly than other silicones, there’s a compromise with viscosity against quality and AS40 is a very good product which many customers favour due to it's technical specification. The product is designed to be translucent, however you could add a little silicone pigment to the catalyst so when you mix the two parts together you will see the colour change, we also recommend degassing this product. If you prefer a product that doesn't require degassing we also stock the CS25 Condensation Cure Silicone. This system does offers a colour change when mixed and self-de-gasses well by nature, a “stretch pour” typically works well with this product so may better match your requirements. If you would like to discuss the suitability of the CS25 for your needs please contact our technical team who will be happy to advise.

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We publish all reviews for verified purchases. Submit your own review and help other customers with their choices.

Shipping Information

This product is safe for all forms of transport. No restrictions apply.

Simply add the item to your basket and then use the Shipping Calculator on the basket page to find the shipping price for this (and any other items).

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