On the exterior side, you should degrease the timber with
Barrettine Methylated Spirit before applying your finish. This will help to degrease the surface and aid the adhesion of the products you apply. Really it depends as to whether you want to have a clear or coloured finish on them. We recommend using a very flexible product which allows the timber to breathe and move whilst offering exceptional durability and weathering such as
Sikkens Cetol HLS Plus followed by
Sikkens Cetol Filter 7 Plus