Monday, 10 June 2013

12 String 335 - Wet Sanding Tru-Oil

So, I'm 6 coats of Tru-Oil in and the guitar body and neck are really starting to look nice. The Tru-Oil has darkened the vintage amber (phew!) and is enhancing the flamed figure in the maple very nicely indeed. Seems that I have followed the directions from Bill at Canadianbreed pretty well, and I'm really happy with the results I'm seeing so far.

Only trouble is, as you may remember, I only sanded my guitar top to 360 grit before the dye and oil went on. As a result, the top and bottom of the guitar really don't feel smooth at all yet, despite a slowly building layer of Tru-Oil. Seems wet-sanding is called for, and plenty of it!

And so, it's Youtube to rescue again. Here you will find is a plethora of advice dispensed on the subject of wet-sanding oil finishes, and Tru-Oil in particular. I hesitate however. Every Youtube article I can find concerning wet sanding Tru-Oil, refers to cases involving natural (ie. undyed) guitar bodies. I was worried that the wet-sanding techniques themselves were somehow smoothing the wood underneath as well as the layers of oil when applied to the guitar. If applied to a dyed guitar body, could they damage the underlying dye job?

Nothing for it but to bite the bullet and plunge on! My first step was to wet-sand to 400 grit (with wet-sanding also planned at 600, 800 and 1200 grits). The process involves a copious amount of oil being applied to the body and to the wet/dry sandpaper and then sanding as per standard established wet-sanding techniques (small circular movements, not staying too long in one place). The difference is that you don't have to keep wetting/rinsing your paper; it just keeps ploughing through the oily slurry that is built up on the surface of the guitar. You sand until this slurry becomes rather too thick to be manageable, and then you wipe the whole guitar clean with a soft cloth.

The results of my first foray into this art were pretty satisfactory. Most importantly, the underlying dye was not disturbed by the sanding and the surfaces feel much, much smoother than before (which is great). Holding the surfaces up to the light, however, I can notice a few marks in the finish  which I think I have caused by not using a block to sand. Looks like the grinding of the sand paper edge (at those moments when the paper got a mind of its own) has made some marks. Fortunately, a subsequent coat of oil seems to cover these. Next time I'll be sure and use a sanding block.

Now for further coats of oil to allow for finer and finer wet-sanding. I'm being rather cautious as I absolutely don't want to sand through at this stage. Although the wet-sanding is done using the oil itself (and you would therefore think that the whole process may actually build the finish rather than taking it away) I am going to assume that the wet-sanding process has taken away most of the build that I started with. Consequently, I'll be applying another 5-6 coats at least before I wet-sand with 600 grit. That's another week of oil application folks!