marine varnish over deck stain
Can you apply a clear sealer or polyurethane over a deck stain? it is not recommended and should really be avoided if possible as it will peel and blister.. ==> thicken the stain up some to keep it on the a pad applicator longer. +1 it's for the verticals. we've got 2,800+sf of decking. that's a lot of railing.... we go through 10 - 12 gals of cabot deck stain each spring. you add some varnish to thicken it up a bit to help application -- but that's all it does.. Sikkens cetol srd (for vertical surfaces, they also have a cetol deck finish) and olympic (several stain and clear products for sidings and for decks) both make good cedar finishes. another alternative, which definitely darkens the wood, is a penetrating oil designed for cedar/redwood.. 
marine varnish over deck stain Paint the deck. use the paintbrushes to apply an even coat of paint. cover the stain completely, but do not worry about putting on a thick coat. it is better to paint smooth, even, slightly thinner coats and do several than to layer on the paint so thickly that it dries in globs. wait several hours for the first coat to dry, then apply a second. The olympic deck stain is already going to have a lot of additive properties to make it water-repellent and uv-resistive. if it has already taken some uv/water damage and has gotten a bit gray, i recommend a good bit of pressure washing/ sanding and a good few coats of stain; if it is new and nice looking still, i recommend spar urethane on its.
