With less than a month to the Uppsala International Guitar Festival and several steps remaining on the build, I will not have a lot of time for finishing. The process I have used before with great success takes several weeks and goes like this:
- Sand down to 320 or 400 grit paper.
- Use cold-pressed raw (boiled dries faster but can turn yellow over time) linseed oil, mixed with turpentine (Canada balsam) in a 1:1 relationship.
- Apply generously to the surface with a non-shedding rag and allow to be absorbed (rags can self-ignite! Put in a completely air-tight bag in between applications and before disposing) and keep doing this until the wood refuses to absorb any more. Wipe off excess and leave to dry. You may be able to apply up to 10 applications in one session before it can’t absorb any more.
- Repeat until even the first application of a coat refuses to absorb. (Each cycle will take longer and longer to dry. It can take over a week towards the end.)
- Now, take wet sanding paper 400 grit to 600 grit and rub in the oil mixture. This will force the wood to absorb a little more. Repeat to 1200 grit paper.
- Leave to dry for a long time….
So, I have dug out what I had laying around and found:
- A bottle of linseed oil (type undisclosed) mixed with carnuba wax and beeswax, intended to be used for kitchen countertops.
- “Danish Oil” – not a very exhaustive table of contents, but here is what Wikipedia says.
- Junckers Rustic Oil
I have applied all three, twice now, to pieces of ebony and maple to see if I can make out a difference. At the moment, I think the linseed/wax oil has a nicer sheen to it. The others have quite strong smells as well. Also, I have used the Rustic Oil on our dining table (which is featured in most pictures on this site) and it turns a bit “milky” over time. Also, it does not provide a very good protection against liquids. I can’t speak for the others, but at least my original process described above impregnates the wood very well.
Lastly, with the rear of the body being swamp ash, I feel that some epoxi finish would be more appropriate to make it harder. I have used this on previous builds where the rear was cedar with good success, but it was a ton of work applying and sanding to get a smooth finish, since the wood absorbed so much.
On the other hand, oil/wax ages more nicely and can easily be repaired. I want to keep the natural wood color, as I have done on all my instruments.
Please share your thoughts with me regarding finishes. I need to get started within the next few days.
I’ve been experimenting with pure Tung oil. It is all natural, expeller pressed from the nut of a plant, non-yellowing, and non-toxic. You can practically drink the stuff. George Nakashima applied five coats to each piece of his furniture: tables, chairs, desks, etc.
So far, I’m very pleased. And it’s good for our planet.
LINK | http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/Behlen_Tung_Oil.html