Finishing wood on al-clad doors..know what your getting in to.
We have a new 10-foot Jeldwen al-clad slider; 4 panels with nine-light style grids. We love the door...BUT. Finishing the interior pine has been a monumental and tedious task. And I've got considerable experience finishing wood. First, the masking of the miles of edges and weatherstripping took half a day. Then, even though Jeldwen used mostly straight-grained pieces, its pine and just doesn't take a stain well even when conditioner is used. The other obstacle was the Cabot water-based poly finish recommended by our installer. Never again! After full two coats with a quality brush, its still splotchy and uneven and requires at least two more to get a good deep gloss. I've seen better coverage from shellac. I'm certain that two coats of honest-to-gosh varnish would have covered it well. I've already put two weekends into finishing the new door. If I was doing it over, I'd buy a pre-finished door or at least one with hardwood veneer interior that stains evenly. If you plan to finish a pine interior, be wary of using a conditioner for the stain even though its recommended for pine. Once it dries (fast!!), the wood won't absorb further stain. And I'll never use water-based poly again. It may be more forgiving, but it doesn't flow and cover like varnish. I'd also do the finishing BEFORE installation so all wood surfaces are 100% accessible without taking the door(s) out of the track again.