I’m Stuck. Wash Coat Before Binding...

[Blake Porter]

1st Build
Stewmac, Triple O, Rosewood, Spruce top

Here’s where I'm stuck.
I'm about to router the body edges for binding. If I add shellac as a protective wash coat, what to do with the shellacked areas after routing?

I have Super Blond shellac (from flakes), but I'm sure this will stain/darken the wood. It's far from clear color. Does the shellac wash coat sand off? ...It did NOT sand off on a test I did..

So how does this protective shellac / wash coat work after the binding’s done?
Can this be sanded (additional sand will be needed on this top)? Does this wash coat need to be applied evenly to entire top? Again, my test shows it will change the color where applied.

Thanks for any help!

[Aaron Helt]

I’ve never used anything prior to binding but after. I use ca glue to glue my binding in. Ca will bleed into the top and then an ugly yellow without a sealer. I haven’t had a problem with the sealer on the top. If you’re going to seal the top with shellac, it would be the same tinting or color.

[Freeman Keller]

I have used both shellac and vinyl sealer before routing binding and purfling channels to prevent chips and fuzzies. Both have sanded back adequately when I was ready to apply finish. When I get ready to finish I apply a full coat of shellac or vinyl sealer to the entire guitar before the finish itself goes on. I don't mind a slight bit of amber in my finish, shellac will be worse than vinyl.

Btw - I too use water thin CA as my binding adhesive because it doesn't seem to affect the finish like either wood glue or acetone glues do. Plus its much easier to tape the binding in place and then spot glue it rather than fighting glue in the channel and trying to fit the binding.

Here is an old guitar with a bit of shellac on the top before and after binding

[Marshall Dixon]

I apply a light coat of dewaxed blond shellac over the top for some protection against dirty fingerprints and grime getting into the wood.

It's part of my finish process anyway as my go-to sealer. My bindings always need to be leveled after glue up and the sealer is reapplied after that process.

I think more importantly when you're routing the binding/purfling channels, that you scribe a line EXACTLY where you want the cut because the bit will cause tearout when it cuts against the grain. Almost guaranteed. I use a Sloan purfling cutter for that.

[Alan Carruth]

So long as you sand back properly the seal coat won't affect the look of the finish. You have to get all of the sealer off the surface, but it won't matter if it's in the pores of the rosewood. The only real issues are if the finish won't stick to whatever you use for a sealer, and if the sealer has different enough properties otherwise. I can't think of anything that wont stick to shellac, so that's not an issue. If the shellac coat is thick, and the finish that goes over it is harder than shellac (nitro, for instance), you will have violated the painter's 'fat over lean' rule. A flexible under coat will move, and if the surface coating can't flex with it it will check. That's a basic technique of 'antiquing'. Another place where a difference in properties can cause problems is if the final coating has a different index of refraction than the sealer. Light gets reflected from the interface, and this results in a 'cloudy' or 'veiled' look. It's especially problematic if you almost get all of the sealer off the surface, since you end up with a splotchy look. The best way to prevent that is to do a really good prep before you apply the sealer, so that you're working with a nice level surface that's easy to clean up. That minimizes sanding later on and insures that you have no low spots that might end up with sealer under the final finish. As always with finish, a few trials on scrap can clear up a lot of questions.

[Blake Porter]

Wow! Excellent feedback!

[Blake Porter]

Might a shellac wash coat effect using pore fillers later on??
Example: spruce top, but rosewood rosette and rosewood sides.

[Alan Carruth]

Again, so long as the surface is properly sanded back, and the finish will stick to the shellac (and I don't know of one that won't) it should be fine. On the top the shellac will be pretty much all on the surface, and will simply go away when you sand it. On the rosette and sides the shellac will be down in the pores, but not on the surface once it's been sanded. Depending on the filler you use sealing the pores can be an advantage, and I've never known it to be a disadvantage.

[Freeman Keller]

Might a shellac wash coat effect using pore fillers later on??
Example: spruce top, but rosewood rosette and rosewood sides.

I only put shellac (or vinyl sealer) on spruce or cedar, I don't worry about the hardwood backs and sides when I route the channel. I really don't call it a "wash coat", I just brush a little around the edges where I'll route. I still get some fuzzies but they sand back easily.

Depending on what you use for pore filling it might be a problem. You normally will not pore fill spruce but I always pore fill rosewood. I do worry about stains if I am going to be applying them.

[Brian Evans]

Late to the party but - I use the Zinsser spray shellac in a can all the time when I am building, I use it to protect the raw wood from dirty fingers, I use it to seal the binding rout, I use it to protect against glue staining so I spray it on the routed ledge and use CA glue to apply the binding (CA bonds to shellac really well). The spray can shellac is around the equivalent of a 2 lb cut fully dewaxed mix, and is handy as heck. If I don't want it as a base coat for colour purposes, I just sand it back to bare wood.