I now use Bore Doctor Oil from doctorsprod.com. I have been convinced by Omar Henderson's research.
woodwind community is loath to change old habits and traditional
materials. Science and experimental evidence not available to these
elders have presented us with a new set of tools and knowledge that
indicate there are better oils, better greases, and better preservatives
for wood and cork than have been used for ages. ...
If you use any bore oil that is clear and colorless you are using the most expensive baby oil (mineral oil) on the planet and petroleum oil is not good for wood in the long term. The only other popular “organic” bore oil has poor antioxidant properties and may turn rancid over time. Other single oils like almond oil will do the same only more quickly. I lived in an old mill town in New England and there would be floor collapses under heavy machinery where petroleum lubricating oils were used over years. Wood, a plant, should be replenished with plant derived oils that have a historical basis (at least 1500 years) for renewing and preserving wood e.g. oils used for wood artifacts in museums or medieval cathedrals.
For bore oil, I use apricot oil from Pakistan. It doesn't turn rancid. All that I know is that it is used by instrument makers in Pakistan. (And that country doesn't seem famous for instrument making.) Apricot oil doesn't seem to harden as much or as quickly as purified linseed oil.
I was interested in your use of Apricot oil for Grenadilla wood but have not been able to find, from a web search, a historical trail for its use as a wood preservative. The fatty acid composition (this is the chemist coming out in me) has 50% oleic and 20% linoleic acid as major components which is similar to olive oil with some natural Vitamin A which I suppose which gives it some antioxidant qualities. The Bore Doctor and of course my Grenadilla Oil have a very different proportion of fatty acids which are similar to the fatty acid composition of native Grenadilla oil. Often natural amounts of plant antioxidants such as Vitamin E and A are not sufficient to keep the oil from turning rancid (a product of autoxidation of fatty acids) so I add a powerful mix of plant derived antioxidants which is much stronger and has kept quality control samples of Bore Doctor in fine condition in my garage (10 -120 degrees F) for the last 12 years. Most sources of apricot oil indicate a shelf life of about a year if kept in a cool dry environment and best kept refrigerated.
was lucky enough to travel widely with my job at the Centers for
Disease Control and was fortunate to talk with museum conservators in
the world’s most noted museums as well as real world caretakers of
wooden artifacts in a number of ancient cathedrals and developed Bore
Doctor as a common thread of a combination of plant derived oils used
for wood preservation developed over several years of research.
Oils put on wood do not turn rancid as quickly as oil in a bottle. And in a matrix such as wood or cloth it takes longer to turn rancid. Not only is a rancid smell bad but in the process of Autoxidation the mono- (Linolenic) and poly-unsaturated bonds in the fatty acid are broken and the result is an acidic residue which can harm wood over time. This is part of Nature’s process of degrading natural products to stable elements in dead or decaying matter.
Back to linseed oil – it is a polymerizing oil (forming long hydrocarbon chains like the process of making plastics) and will over a long time form a hard impermeable surface but in the interim it forms a partially polymerized gunky, sticky layer. I believe that sealing wood completely is not a good thing because it is never 100% and those areas that are not sealed or the sealing has been lost will quickly absorb excess moisture leading to areas of greater hydraulic pressure in those areas as opposed to dry sealed areas which physics tells us may lead to cracking.
I believe that wood should be allowed to “breathe” though the natural pores in the wood. Water is taken in or expelled through these pores and not the entire surface of the wood. In this way wood can maintain a moisture balance more easily within the wood. The oil in the wood too is a grand part of Nature’s complexity. These plant oils also maintain a moisture balance because since in plants they have to interact with water they have special properties where different layers of water are held by hydrogen bonding to the lipid core. The initial layers are bound much more tightly than succeeding layers of water so excess water on the oil surface take less energy to remove then inner layers which are held more tightly. This allows the wood to expel excess water easily and maintain and hold the last layers of water on its surface as a last critical moisture reservoir. This is why dry wood will lose oil more quickly because some of the oil it is no longer holding moisture and the partial vapor pressure of the oil is diminished.
philpedler: The last paragraph particularly convinced me to change to Bore Doctor.
I have repeated the lesson several times on Woodwind.org but the same old questions keep coming back over time and I am just tired of repeating and then someone will will praise using Yak fat grease for the past 50 years and the science gets lost. ... The community is slow to change and the big guys do not want the masses to know that real science abhors their petroleum based crap.
Well, cork is wood too and petroleum based cork grease with eventually destroy the cell walls of the cork and they will rupture, collapse, and not rebound as they should to give an airtight seal. Cork cells are sealed cubes and the cell walls are elastic which allows the cells to be compressed and then rebound to their original shape and petroleum will shorten this capability. Petroleum products will also dissolve the glue holding the cork to the tenon – called spinners which I am sure that you have seen in your work.