Silicone Rubber Products
When it comes to choice between Platinum Cure silicone vs Tin Cure silicone you have to look at the application to which you are going to use the mould. Both silicones can be used in exactly in the same way and for the same tasks your activity will determine which silicone you will choose in the end.
In order to avoid long and complex explanations the simple answer to the above situation is as follows
The chemical difference between tin-cure (condensation cure) and platinum-cure (addition cure) silicone mold making rubbers lies mainly in the metal used to catalyze or cure the base rubber. The metal tin is used to catalyze or cure tin silicone, and platinum is used to cure platinum silicone rubber. Accordingly, tin-cure silicone rubbers are usually significantly less expensive than platinum-cure ones.
Tin cure:
If you have a general application that you are going to use the mould for such as making candles, working with cement, casting resin item, using material that have no platinum in the formula then you can look at tin cure silicone.
This said these types of silicones can be used with food substances simply because it functions in the same way as food safe platinum cure silicones, however the catalysts and the material is not certified or approved to be used with food. In short the catalyst is not human safe and the silicone itself has not been manufactured in a food grade facility.
In many situation people do use tin cure silicone for things like icing and chocolates as the food is not in contact with the silicone for extend periods or the mould is not used in the making of the food item such as when you are baking a cake. Once silicone has reacted and set the material is basically “inert” and “safe” added to this you can apply a post-production treatment of soaking the silicone in water overnight and then baking in the oven at 90 degree centigrade for 45 min to drive off and reduce any residues and helps to leach out harmful levels of tin and peroxides that are used in the catalytic reaction in the setting of the rubber manufacturing process of the mould. This will render the silicone as "safe" and as such many people find that they are comfortable to use it in the above situation.
Please note that this will not render the silicone certified food safe and if you do choose to do this it is completely at your own risk. Tin cure silicone is also not body safe. In addition to this we have to stress that it is important to know what system your catalyst system your silicone is using as well as been aware that some silicones have additives in them to prevent moulds and fungi, as in the silicones used in the bathroom. Not all silicones are born equal.
Platinum cure
These types are silicones have been produced in a factory that is certified food safe and clean, and the platinum cure silicone catalyst is also made in such a way that it is human safe. In most situations the only time you look at platinum cure silicone is when you are preparing the food in the mould or you are looking for a silicone that is more chemical stable. The other time you need to make use of the food safe silicone is where you require that the perpetration material for the food is all certified food safe or that you are in a public situation where food safe standards are required.
One other important things to note is all mold making rubbers may be subject to cure inhibition by contaminants on the surface of a model being used for mold making. Silicone rubber is sensitive to sulfur that can be found on different surfaces and are present in some types of modeling clay. Platinum-cure silicone rubbers are critically sensitive to sulfur and will not cure under any circumstances when exposed. Tin-cure silicone can cure over models containing sulfur if the model surface is first thoroughly sealed with an acrylic spray.