Topcoating the roof
Preparation for topcoating
Taking care and paying attention at this stage will produce a roof of superb appearance. Using a sanding pad with a 40 grit sand paper, lightly sand the corners and trim bandages. Sand off any unsightly fibres, taking care not to sand too heavily on the corner itself as this may lead to holes appearing. Cut any excess cured mat protruding beyond the trim with a sharp Stanley knife.
Seal any edges with abutting walls using a clear silicone sealant. Fit any C100 simulated lead flashing before top coating and seal off with a clear silicone sealant.
Topcoating the roof
The Topcoat is a resin and should be treated in the same way as the base resin. It requires the addition of catalyst for it to cure.
Always try to apply the topcoat immediately after the laminate is semi-cured (can be walked on, no stickiness.) If this is not possible then ensure topcoating is carried out within 24 hours to gain a good bond with the laminate. If the topcoating is left longer than 24 hours then wash down the laminate with acetone to gain a good cross-polymerisation of the topcoat to the laminate.
Mixing the topcoat
Calculate how much topcoat you will need to use to cover the main body of the roof (topcoat is applied at a rate of 0.5kg/m2.) Add the required amount of catalyst and stir well.
If a coloured topcoat is needed rather than the standard pre-pigmented grey, a colour pigment will need to be added to a clear topcoat. A 20 kg tin of topcoat requires 2kg of colour pigment. It is essential to mix the pigment thoroughly into the topcoat to avoid patchiness and uneven colour.
Remove the lid and stir the topcoat well before use. Ensure the styrene & wax at the bottom of the tin is fully mixed in. Pour enough topcoat out into the mixing buckets to cover the perimeter of the roof (including the edge trims.)
Applying the topcoat
Using the 7” polyester roller, cover the remaining laminate with just enough topcoat for the fibre pattern to be visible. Do not coat the roof too thickly or the topcoat
will crack.
Use a 2½” Polyester roller to coat the trims. A roller will get a better and more even finish than a paintbrush. Roll the topcoat along the face of the trim. Hold the roller at an angle to the bottom of the trim to cover half of the radius return on the front of the trim. To protect the fascia from topcoat, hold a piece of flashing trim against it as you topcoat the radius on the underside of the trim.