A Finishing Question

[gsmittle]

I'm about to build several bookcases for our basement (Birch ply with maple face frames). I'm thinking about spraying the pieces with shellac, then wipe on poly, then cutting the dados and shelf pin holes.

I'm wondering if this is a good procedure, or should I wait until the carcass is together before spraying?

Also, any tips for making the pin holes blend with the finish? The raw wood inside the hole drives me crazy. I'm wondering if I dab the holes with shellac if the pins will still fit.

Thanks!

g.

[cabinetman]

I would do all machining, assemble and then do the finishing. If you can spray, I would use waterbase polyurethane. You can plunge a Q-Tip with finish in the shelf pin holes.

.

[radhak]

I've always wondered about finishing first, assembling later, to make the finish easy and even. But being lazy, always ended up building the workpiece and finishing later - though that always brings about the extra effort while finishing the corners and hard-to-reach places.

If you want to, I'd say you should cut the joints, drill the holes and do everything but the final assembly before you finish the parts. Why? So that you don't spoil a hard-rubbed finish while cutting or dado-ing. Of course now you have to worry about protecting the to-be-glued areas from the finish. Never an easy life...!

By the way, you do know that regular Shellac does not go under poly, right? You need the special, de-waxed one (eg Zinnser BullsEye Sealcoat, found mine at HD).

[cabinetman]

I've always wondered about finishing first, assembling later, to make the finish easy and even. But being lazy, always ended up building the workpiece and finishing later - though that always brings about the extra effort while finishing the corners and hard-to-reach places.

If you want to, I'd say you should cut the joints, drill the holes and do everything but the final assembly before you finish the parts. Why? So that you don't spoil a hard-rubbed finish while cutting or dado-ing. Of course now you have to worry about protecting the to-be-glued areas from the finish. Never an easy life...!

Another plus is that if the finishing is done after assembly, any problem areas can be addressed.

.

[gsmittle]

By the way, you do know that regular Shellac does not go under poly, right? You need the special, de-waxed one (eg Zinnser BullsEye Sealcoat, found mine at HD).

Mark Spagnolo did a trial fairly recently that compared dewaxed and waxy shellac under poly. After some time had elapsed (several months, I forget how many) there were no adhesion problems in his sample.

I'm using dewaxed blonde flakes, mixed a month or so ago, so the point is probably moot.

g.

[JimD]

I never tried it but I have read about people pre-finishing plywood, especially for kitchen cabinets. One guy used a pad applicator and used oil based poly. I think you need to plan on a final coat after assembly because you'll nick it some cutting putting it together but even so you could save time.

I don't know why you want to put shellac on birch plywood. It helps pine not bleed through but I don't see what it does for birch. I'd just put the poly on. I'd spary, because I have a nice spray rig (Fuji HVLP) but if I didn't have spray capability I'd consider a pad applicator or a roller on the plywood before cutting it up. You can put the finish on while the wood is horizontal which is a big advantage. But nothing is easier and faster than spraying if you have the tools. Cleanup takes longer than application for most of my projects (I spray exclusively water cleanup finishes).

Jim