Date: Sun, 08 Jun 2003 13:28:20 -0400
From: Pat Missin
Subject: Re: sealing wooden combs (long!)
Forgive me if the following post is overkill, but I've been meaning to
put something together on this topic for some time.
Few terms seem to be misunderstood or misapplied as much as the terms "toxic" and "non-toxic". My wife (with degrees in both chemistry and chemical engineering, as well as several years experience with one of the world's largest pharmaceutic and cosmetic manufacturers) usually dismisses the term "non-toxic" as a label claim - ie. it is an almost meaningless term that companies will put on their products to reassure customers that they are unlikely to die as a result of using said products.
Toxicity is relative. There are many things that are good for you in small doses, that are extremely bad for you in large doses - eg. certain vitamins, fluorides, etc. A label claim of "non-toxic" means really very little, other than you are unlikely to find large amounts of arsenic or lead in it.
Things are tested under conditions termed "normal usage". A bug spray that is "pet safe" assumes that you don't pin down your cat and force him/her to inhale the spray for several minutes. In the case of a salad bowl sealer, or a sealant termed safe for food utensils or children's toys means that they are safe when used in a manner that would be considered "normal usage" for said items. Whilst that may include oral contact, it is unlikely to have been tested under circumstances which include sticking it in your mouth and rubbing it from side to side whilst frantically blowing and sucking. Even something which has been approved for use on the mouthpiece of a woodwind instrument does not have normal usage conditions identical to a harmonica - abrasion and inhalation being the most obvious points. However, normal usage for the diatonic and the chromatic is different - any sealed wooden parts on the chrom are not going to be abraded against your lips or tongue, so you can afford to be much less picky about sealants for the chromatic.
"100% natural" - this may be a good selling point in a health food product, or whatever, but it does not guarantee that something is any better than a synthetic version. Many natural products contain far higher levels of contamination than equivalent synthetics would ever be allowed to contain.
When pondering the safety of substances, we also have to consider what is termed "route of entry", as well as the degree of exposure. Many things (Teflon coating is a great example) can be extremely hazardous during application, mostly from an inhalation point of view. However, during normal use (see above), the end user is not exposed to these dangers. After a suitable degassing period (I usually gave mine at least two weeks, but that is almost certainly overkill), urethanes (even oil based ones, although I would never recommend them for use on harmonicas) should not pose any significant inhalation risk to the user. Degassing from a new carpet, or any plastic products in the home would almost certainly be a greater hazard. I would also doubt that the quantities that could be taken into the body via ingestion would be so small as to be harmless, even if the user is actually eating their harmonica.
Beeswax is often suggested as a "non-toxic" "all natural" sealant for the harmonica. The problem with beeswax is not one of toxicity or allergies (although there are inevitably some folks who will be allergic to it and to them I expect it is a big problem), but that beeswax is a well-known sensitising agent. Some people are more tolerant than others and in the case of a harmonica, it may be hard to tell whether it is contact dermatitis brought on by the wax surface, or by the nickel or chrome plating used on many harmonica covers.
Yes, lipsticks often use beeswax as an ingredient - certainly cheap lipsticks do! There are also some of the "100% natural" types (see above) that proudly boast of the beeswax content, but mostly it is used because it is cheap. The better the brand of lipstick, the less beeswax it contains. My wife designed many top name cosmetics (Max Factor, Cover Girl, etc.) and there if there was one ingredient which would always trigger warnings from the health departments, it was beeswax, simply because of the number of people who would have an adverse reaction to it, even when it was only present as a very small part of the blend.
It is possible (in so far as I would not state that it is definitely impossible) that you could get a sensitisation response from water-based acrylics, or those products sold as water-based urethanes. The sensitisation issues from beeswax (and lanolin, etc.) are due to proteins. Unless there is something horribly wrong with my knowledge of water-based polyurethanes and the like (which, I must confess, is possible!), they are not protein based.
Again, if you are dealing with chromatics, then sensitisation is not really an issue. If you are using sealants on diatonics for your own use, then you can quite easily determine if you have any adverse reactions to any particular substances. If you are sealing wood combed harmonicas for others, things are not so straightforward. This could well be the reason that Hohner (who manufacture harmonicas by the thousand in a country with strict health regulations), aside from a lick of paint around the edges, choose NOT to use sealants on their wood combs.
Here is a discussion on sealants for wind instruments that may be useful, bearing in mind that normal usage for a clarinet or recorder is somewhat different to normal usage for a harmonica.
http://www.mimf.com/library/wind_finishes.htm
Pat Missin - http://www.patmissin.com