Re: [Harp-L] comb questions

["Tim Moyer" <wmharps@xxxxxxxxxxxxxxxxxxxx>]

Jonathan Ross wrote:
> To the best of my knowledge, neither Joe, Richard nor their 
> partner Jimmy Gordon have ever definitively answered this 
> question in public. From what they have said, it is a form of 
> urethane-type varnish which is labeled "child safe".  

There are sealants on the market that are specifically intended for 
food service implements and child's toys, both of which are expected 
to come in frequent contact with the mouth or other material that 
may be ingested.  These are generally referred to as "salad bowl 
finishes" and can be purchased from any good woodcrafter's store.  
They typically require several coats and are non-toxic after 72 
hours of curing.  Behrens and General Finishes both make good 
products, and I have used them both.  

Some finishes, such as shelac and tung oil, are more suceptible to 
wear than others.  Shelac is completely food safe -- it is actually 
used as a polish on food like apples -- but these do have more 
problems with required recoating than the salad bowl finish 
mentioned above.  

Generally, when sealing the stock harmonica comb, most of the 
original finish remains intact, and the new sealer is applied to 
the "raw" surfaces -- the mating surfaces for the reed plates, as 
well as the inside of the channels, and any new raw wood that might 
be exposed through finishing.  The amount of this area that actually 
comes in direct contact with the skin is minimal.  

Mr. Ross continues:
> I believe the type of wood Hohner has used (thus the most  
> "traditional" in the US market at least) is pearwood.  I'm 
> not sure if this is still the case, but pearwood was what 
> the wood was called.  Exactly what pearwood is, and if this 
> is a specific or a generic name (ie, "poplar" and "pine" cover 
> a lot of ground) is something I couldn't say.

Marine Bands currently use pearwood -- the wood of the pear tree -- 
though in the past they've used peachwood (wood from peach trees).  
These woods are generally free of heavy grains, low in knots, grow 
quickly in cultivation, and have the added benefit of allowing 
producing fruit!  It's easy to mill, and is light and fine grained.  

Hohner also uses doussie wood in the combs of it's MS Blues Harps, 
and formerly in the MS Marine Band (now discontinued).  Doussie is 
somewhat more dense than pearwood and has a somewhat stronger grain 
pattern.  As a result, it's slightly more brittle to mill, but is 
not as suceptible to moisture absorbtion than pearwood.  

When considering "superior" woods for comb production, you might 
consider whether another non-wood material is superior to any wood.  
I think Vern Smith proved to us a few years back that combs can be 
made from nearly any material (he made combs from concrete, balsa 
wood, and styrofoam, among other materials), and cast serious doubts 
on the idea that the material of the comb makes a perceptible 
difference in tone.  

If not a tonal difference, then what?  Wood certainly looks nice, 
so, why not pick the nicest looking wood?  Aside from that, I'd say 
that plastics and metals are more dimensionally stable and are 
cheaper and easier to form than wood.  They each have their own 
problems, however, and the choice of comb material tends to be 
highly personal among players.  Be aware that some woods can cause 
highly alergic reactions in people, so you can't choose a wood 
solely on it's appearance (cocobolo, ebony and mahogany, among 
others, are known to cause skin rashes).

> Beeswax will do it, however it does have some distinct negatives 
> (and these are in the archives).  First, it does burn, and more 
> than one person I know has burned themselves trying to seal combs 
> with beeswax.  Of course, this can be done safely, but it's 
> something to consider (and personally I'd ask myself if I wanted 
> to bother with the effort compared to just using a varnish).  
> Second, it can melt out of the comb.  Now, most people won't get 
> their harmonicas hot enough for this to be an issue, but, again, 
> I'd rather avoid it. Third, some people do have a contact reaction 
> to beeswax, and even if you don't have such immediately, contact 
> reactions can develop over time with repeated exposure.

Beeswax, like all the other sealants, has positive and negative 
points.  Yes, beeswax is flamable (it's a candle material, after 
all), and as such should be handled with caution.  Never hear 
beeswax directly over an open flame.  Don't try to extinguish a 
beeswax fire with water.  Beeswax could remelt out of a comb, but 
I've never seen this happen, and I live in Texas where it gets HOT 
in the summer.  The idea in beeswax sealing is to get the wax *into* 
the wood, not onto the wood.  Once in the wood, it's highly unlikely 
to migrate back out again, even under extreme heat.  The wax is 
specifically polished off of all the exposed surfaces of the comb, 
to prevent extraneous wax from re-liquifying and running out.  Also, 
unlike some parafins, beeswax has a fairly high melting point (146 
degrees F), which isn't that commonly achieved in people's 
instruments.  As to the possibility of a contact reaction to 
beeswax, this is highly unlikely.  Beeswax is used in a number of 
common cosmetics, and carries no material warnings for skin 
contact.  What's somewhat more common, however, is the beeswax 
acting as a sensitizer for reaction to other materials.  

Beeswax is cheap, easy to apply, and leaves a pleasant taste/aroma 
in the comb when it's finshed.  It's also not all that effective as 
a sealant, only retarding and not preventing the absorbtion of 
moisture into the comb.  It should be sufficient for most people's 
use, but I have customers who specifically have problems with the 
incomplete seal of beeswax, and I've replaced beeswax sealed combs 
with varnished combs for some people.  

> If I were making combs I would consider the material first and 
> what properties are best for the job (hard, inert, easy to work, 
> etc...), then address whatever issues come up secondly.  If it is 
> a wood or wood-composite which needs to be sealed, I would then 
> look at what is the easiest and safest way to go.  A good quality 
> varnish designed for objects which are intended to go in the mouth 
> (kitchenware, toddler toys, etc...) will probably be a bit more 
> expensive than a chunk of beeswax, but a lot easier to work with 
> and do at least as good a job, if not better.  To me, ease of work 
> is a big part of it. I don't know how long it takes to seal a comb 
> with beeswax from start to finish (melting wax, sealing comb, 
> letting comb dry...) but I do know that I can apply varnish from a 
> paint can over the surface of a harmonica comb in no more than a 
> minute.

Very sound advice indeed.  

Food-safe sealants are, in my opinion, better sealers than beeswax, 
but both perform well in typical applications.  If you need to rinse 
your harps with water and don't dry them out completely, the beeswax 
sealed comb might swell a little, though it should return to normal 
once it dries.  Beeswax can be applied in one step, though 
afterwards the excess wax needs to be removed from the comb, which 
can be painstaking.  Varnishes are simpler to apply, but these are 
wiping varnishes, and the excess needs to be removed before drying.  
Also, these varnishes take more than one coat, so allow for some 
drying time between coats and a significant curing time after 
coating before assembly. 

-tim

Tim Moyer
Working Man's Harps
http://www.workingmansharps.com/