Home Installation Guide Traning manual Stage 4 - Topcoating and Finishing

Stage 4 - Topcoating and Finishing

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 good bonding 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.

Remove the lid and stir the topcoat well before use. Ensure the styrene and wax at the bottom of the tin is fully mixed in. Pour out into the mixing buckets enough topcoat to cover the perimeter of the roof (including the edge trims.) 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.

Calculate how much topcoat you will need to use to cover the main body of the roof. (See material estimator in the Commercial Manual).

Add the required amount of catalyst and stir well.

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. If a coloured topcoat is needed rather than the standard cool grey or dark admiralty grey, a colour pigment will need to be added to a clear topcoat. A 20 kg tin of topcoat requires 2 kg of colour pigment. It is essential to mix the pigment thoroughly into the topcoat to avoid patchiness and uneven colour.

Cleaning Tools and Equipment

Buckets can be re-used for many jobs. When each mix is finished with, coat the inside of the bucket. When the resin has cured after approximately 30 minutes it can be peeled out, leaving the bucket like new and ready for the next job.

Paintbrushes can be dropped into a re-sealable container of acetone and left for the next job. Use only paintbrushes that have unpainted or uncoated handles, as the coatings will come off and contaminate the resin. Polyester rollers have sleeves that are removable. It is too time consuming to clean the roller sleeves. Unscrew the nut with pliers and drop the used sleeve into the bucket of used resin.

Either use disposable latex gloves when handling catalysts or resins or clean hands with hand cleaner. Do not clean hands with acetone. Wipes are also a useful addition to your toolkit. As well as cleaning hands they are good for removing resin from windows and fascias.


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