Mineral oil after sanding body

[Hurricane Bob]

My friend just sanded down his old acoustic guitar and removed some of the lacquer and then used mineral oil on the back and sides. He claims it sounds better that ever. Is this a good idea? What would be a better but nontoxic alternative?

[fazool]

Originally Posted by Hurricane Bob

My friend just sanded down his old acoustic guitar and removed some of the lacquer and then used mineral oil on the back and sides. He claims it sounds better that ever. Is this a good idea? What would be a better but nontoxic alternative?

Mineral oil is non-toxic.

Baby oil is mineral oil with perfumes and other additives.

This is a very odd choice: to remove the protective lacquer finish and then add oil.

[Rodger Knox]

Originally Posted by Hurricane Bob

My friend just sanded down his old acoustic guitar and removed some of the lacquer and then used mineral oil on the back and sides. He claims it sounds better that ever. Is this a good idea? What would be a better but nontoxic alternative?

That is possible, but highly unlikely. Mineral oil is a non-drying oil and will provide no real protection. It will soak into the wood and make it heavier, not usually a good thing. Most "oil finishes" are actually oil varnishes, and there are a number of formulations for different applications. Most of these are no longer available, and have been replaced with some type of poly.

[charles Tauber]

He has just reduced it resale value to near zero. Perhaps that doesn't matter to him.

As both Fazool and Rodger commented, a poor choice from every perspective.

Fully cured film finishes - lacquer, varnish, poly... - are non-toxic. Ideally, one would have a very specific reason for removing a finish from an instrument.

Finishes can be divided into two general categories: film and penetrating. Film finishes, such as lacquer, varnish, poly, shellac ..., adhere to the surface of the wood. Penetrating finishes, such as most oils, penetrate into the fibres of the wood. Film finishes can readily be removed, while penetrating finishes, generally, can't. Once a penetrating finish has been applied, short of removing the wood to the depth of the penetration, it is largely permanent.

Most penetrating finishes - generally oils, such as tung, walnut, pure linseed, "Danish", etc. - have a low lustre. If one wants a low lustre, that is one possible choice. Generally, they are easy to apply and difficult to do badly. But, as Rodger pointed out, can add mass to the wood and make is sound "thick" or muted. It would not be my choice to use a penetrating finish on most instruments. Oils usually darken woods to which they are applied and can be absorbed unevenly, depending upon the wood, making the wood look blotchy. Obviously, natural oils like walnut, olive, almond or pure linseed are "non-toxic", but part of what makes them non-toxic is that they don't have any driers added, and won't dry (harden). They will, often, oxidize (go rancid). Penetrating finishes, generally, offer little to no protection to the surface of the wood.

Film finishes can, generally, achieve any level of lustre from matte to high gloss. Shellac dissolved in alcohol is about as non-toxic as it gets - people drink alcohol and shellac is often used as a glaze in food preparation. Generally, applying film finishes so that they look good on an instrument takes some skill. They can be applied with brush, pad, or most often, sprayed. I don't recommend it, but bee's wax could be used as a very thin film finish, though it would offer nearly no protection against moisture or bumps.

In answer to your question on what is better than mineral oil, nearly anything. What to chose depends upon your skill in applying it, the tools you have with which to apply it and what appearance you want when it is completed. 3-in1 oil should not be an option.

[davegoldbeard]

Originally Posted by Hurricane Bob

My friend just sanded down his old acoustic guitar and removed some of the lacquer and then used mineral oil on the back and sides. He claims it sounds better that ever. Is this a good idea? What would be a better but nontoxic alternative?

It's not a 'non toxic' option but in some cases (mostly when I make ukuleles) I use a gun stock polishing oil which dries. When using any oil it is of course important to seal the timber first so as to prevent the oil from simply soaking in. Applying oil to a sealed timber means it stays closer to the surface, and a good quality oil that dries can provide a very nice looking, durable finish that won't ruin the sound.

[Rodger Knox]

Originally Posted by davegoldbeard

It's not a 'non toxic' option but in some cases (mostly when I make ukuleles) I use a gun stock polishing oil which dries. When using any oil it is of course important to seal the timber first so as to prevent the oil from simply soaking in. Applying oil to a sealed timber means it stays closer to the surface, and a good quality oil that dries can provide a very nice looking, durable finish that won't ruin the sound.

Ah, yes. TruOil is actually an oil varnish, and is used by many amateur builders, myself included.

[Ned Milburn]

Are you sure your friend applied "mineral" oil and not some other finishing oil??

[Hurricane Bob]

Yes, my friend applied Mineral Oil and recommended it to me. Guess he should have used lacquer, varnish, or shellac.

[redir]

With friends like that who needs enemies

It always amazes how and where people get their ideas from. And I admit I've had some pretty crazy ones too and the luthier community is often times guilty as charged. Mineral oil is for your baby's butt

[charles Tauber]

Originally Posted by redir

Mineral oil is for your baby's butt

And as a recommended lubricant for my air compressor.

[B. Howard]

Originally Posted by Hurricane Bob

Yes, my friend applied Mineral Oil and recommended it to me. Guess he should have used lacquer, varnish, or shellac.

Well it's too late now. The mineral oil will have contaminated the wood so virtually no other finish will adhere long term.

[rick-slo]

Originally Posted by Hurricane Bob

My friend just sanded down his old acoustic guitar and removed some of the lacquer and then used mineral oil on the back and sides. He claims it sounds better that ever. Is this a good idea? What would be a better but nontoxic alternative?

What has already been said but at least:

1. he did not mineral oil the top
2. it sounds better than ever to him