When to spray wash coat?

[Micha Schellhaas]

Hi guys,

I'm back again hoping for your expertise - my first electric guitar builds are well on the way, 4 Les Paul style guitars.

I was reading more about spraying a wash coat of clear that you later sand down when you continue working on the piece. I understand that you can seal a body from outer moisture like that if you need to ship it, I was wondering what's the proper time to use a wash coat?

I will most likely build 4 guitars up until the spraying the finishes, and then put 2 of them on "pause" and only finish 2. I guess here's when you apply a wash coat for sure.

But do I need to worry If I have a body with a ready carved top lying around for 2 weeks, do I need to necessarily seal it or treat it in any way? what about storing necks...

[Jeff Highland]

If you still have finish sanding to do it is not so much of an issue, though sealing the endgrain is a good idea if there is any possibility of  humidity change.

If you are at or near final sanded condition then a seal coat also provides protection against accidental staining or insect poop damage.

[Russell Vance]

Hi Micha,

If you have semi finished bodies sitting around there are a couple of things you can do as precautions:

Firstly, if you are leaving bodies around for later either leave them with a millimeter or two of final thicknessing to do. Firstly it gives you something to remove when the inevitable bumps and nicks occur with stuff left for later (unless you have secure area that you wont be going near). 

Secondly and more importantly, maple caps laminated to mahogany and left unfinished over time will "cup" when the relative humidity/temperature changes through a season and they will stay cupped as the dissimilar timber finds equilibrium.  And, most bodies left unfinished will cup anyway if left for a couple of seasons.     Before we use a stock body we put it across the jointer and the thicknesser before final sand and prep so its flat - simple as that.

When we cut KD blanks we usually tape over the endgrain with shiny packing tape just as a temporary barrier as the new wood finds its balance.   But we are in a fairly stable relative humidity where we are and it's never been a problem.

I don't spray my blanks with a washcoat - it serves no purpose as we final dimension just prior to build anyway.  And a skinny washcoat affords no protection from Rh changes or physical damage anyway.  I presume you are talking nitrocellulose or skinny poly here?

Good luck with storing semi-finished necks - unless you have climate control and perfect KD timber you are going to have a pretzel if you finish carve and do not fully build (fingerboard/truss rod) up the neck - especially one piece necks - ie non laminated.    We cut our 3 piece neck blanks to a semi-finished profile and plan and then final machine them just before the fretted fingerboard goes on.  Not unusual to take 3 mm off the final dimension to get everything true and you need to skim the fretboard surface for a clean new gluing surface anyway.

That's a bit of what we see.

Rusty.