Most transparent oil for neck?

[DC in ATX]

After doing more research, Osmo is off the table for the same reason that Rubio Monocoat is off the table. I have worked the neck beyond 150 or 220 grit.

This is the neck under natural light after I burnished it earlier this week:

Based on my test swatches, I am comfortable putting oil, varnish or schellac on the neck. I can open the grain and those finishes will penetrate the wood to some extent. There’s some precedent on the different instrument finishing forums for applying these types of finishes to a burnished neck.

That’s not the case with these modern oil finishes. The manufacturer’s instructions for Osmo or RMC are very specific about the raw wood prep. I’d rather not take the sanding backwards at this point.

I’ll try a couple different test swatches over the weekend, including Tung oil and garnet shellac.

 

[rudy4444]

I think you've come to a reasonable conclusion based on your particular preferences for surface preparation.

I've been doing furniture and instrument building for over 30 years and followed recommendations by product manufacturers to go no finer than 220 for surface preparation. (Finer sanding is reserved for leveling and buffing applied finishes to higher gloss levels, of course.)

Doing a final pass with 220 in the direction of grain has always been acceptable to me and that is still OK for applied finishes of every type to have enough surface tooth to bond to or soak in on all types of wood.

Finish manufacturers often caution against "over sanding", with the warning that it can seal the pores of the wood. Here's a surface sanding and preparation guide from General Finishes, a company that supplies products that many woodworkers are fond of. Notice the even bold their "Do not over sand" caution.

Preparation & Sanding

Their recommendations align with everything I've previously read from other finish suppliers.

Since you're looking for a totally transparent finish I'm assuming you've read the "rather lengthy" topic and the recommendations for Varathane?

Using water based products for instrument finishing, Target Coatings 9000 6000 and Varathane WB

 

[Arie X]

Sold! That stuff is everywhere around me here in boat-owning-building-and-repairing land. What are the other two parts you mix with it?

1 part epifanes clear varnish, 1 part epifanes accelerator, and 1 part epifanes thinner. the accelerator turns the long chain resin to a short chain resin increasing the hardness and the thinner turns it into a wiping varnish.

application as with other varnishes used in instrument work, is finicky and you need to plan and execute well and ventilation is required. be aware also that this stuff while sold as "clear" -it's not water white. it has the typical amber tone of the species.