Silicone Sealants Information

City Plastics stock and sell a range of silicones and sealants.

All silicones and sealants that are stocked by City Plastics are the materials that we use for our own jobs.

Do you realise that most silicones will not stick to most plastics?

The type of silicones and sealants that we stock is determined by our own extensive testing, we continually test all products for adhesion to plastic sheet.

As a guide, City Plastics will advise on what material we would use to do a particular job, however we do not make any recommendations or guarantees of any kind as to the suitability of the material for the job in question.

For the purpose of our own internal testing, all Silicones and sealants are tested for adhesion to Acrylic and Polycarbonate.

Dow Corning 791, Silicone building sealant
This particular product is the one that City Plastics has had the most success with and is regularly used for in house jobs. Recent tests on untreated surfaces have shown that when used in direct sunlight, the sealant will not properly adhere to the plastic, however when applied and allowed to cure in the shade the adhesion is good. Tests were also carried out on materials where the surface was lightly sanded with 600 grit paper, when this was done the sealant adhered very well in both sunlight and shade.

Dow Corning 580, Glass, metal and masonry sealant
This particular product is also used by City Plastics and is regularly used for in house jobs. Recent tests on untreated surfaces carried out in direct sunlight and shade have shown that the sealant will not properly adhere to the plastic. Tests were also carried out on materials where the surface was lightly sanded with 600 grit paper, when this was done the sealant adhered well in both sunlight and shade.

Sikaflex
When used by itself has proven to be unsatisfactory.
However when used as recommended by the manufacturer. IE sand plastic surface, paint with blackout primer and apply the correct thickness of sealant, it seems successful. It should also be noted that Sika recommend a UV impenetrable cover over the blackout primer, apparently the primer is not UV resistant.

Download silicone information as a PDF file