Most of the sealants used by the home handyperson are grouped under three basic headings: acrylic, silicone and co-polymer types.

Acrylic Sealants

These sealants are ideal for filling gaps. They are paintable and remain flexible even after drying. An example is Selleys No More Gaps. This type of sealant is excellent for use indoors or outdoors to fill cracks and gaps that expand and contract with the weather. You might, for instance, fill in a gap with rigid filler during wet winter months and then in the dry summer months you find that the filler drops out. You should use an acrylic sealant for this job. They can be used around doorframes, windowsills, skirting boards, cornices and almost any other area where expansion and shrinkage causes problems. Most brands of acrylic fillers are water clean up, skin over in less than an hour and cure in two days. Painting can be done as soon as the sealant skins over.

Silicone Sealants

These tend to come in a variety of types for specific jobs. For example, Window and Glass sealant is an acid cure sealant whereas Brick and Concrete sealant is a neutral cure sealant. You must be careful when purchasing silicone sealants that you get the correct one for the job in hand. Most manufacturers have tried to make life easy for the consumer by giving names to their products that tie in with the product usage. Selleys for example use product names such as Window and Glass, Brick and Concrete, Roof and Gutter, Bathroom and Kitchen and so on.

Co-polymer Sealants

These can be used on most metals, plastics and substrates. (Selleys All Clear or Selleys Wet Seal are examples.) One of their many features is that they can be used in damp conditions and some can even be used in very wet conditions as well. In many ways co polymer sealants are universal in the surfaces that they will stick to and being neutral cure, will not cause any damage to those surfaces.

A Few Tips When Using Silicone Sealants

Prepare the surface. Clean off all traces of the old sealant (if there was one) and make sure that the surfaces are clean and dry. In bathrooms or kitchens be extra careful in getting rid of fats and soap scum. Wash with a mild bleach solution to get rid of any mould spores. If you are on a metal surface, make sure that that there are no rusted areas and prime any bare metal. Apply the sealant you are using on the same day that you clean the surface you are going to work on. Most importantly, READ the manufacturers instructions carefully before use (including all the safety information).

The key to successfully using silicone sealants is that you really need to purchase the correct sealant for the job in hand. Go to your local Mitre 10 store where experienced staff can advise you.

Written for Mitre 10 by Chris Bennett Homehandyman.