Hearing Aid Repair & Modification Using UV Materials
Part One: Shell
I had the privilege of visiting a small hearing aid
manufacturer in Maine recently, where I got to meet some very talented
people. I had been invited there by the company manager to show some of
our equipment, and to talk about using UV technology in their repair lab.
As it turned out it was a very busy day for them, and being a small
company they didn’t have a lot of time to spend with me. However, it was a
great time to do some “looking-on”, so I did.
In the 90 minutes I spent with the company, several
customers came in for varying reasons, but two in particular had the same
complaint. Their hearing aids were fitting a bit loose and both were
feeding back. On both occasions, the technician took the hearing aids back
to the lab and using a small brush applied some clear fingernail polish to
the hearing aid shell. After waiting 10 minutes for the polish to dry the
hearing aids were delivered back to the customers who were thrilled to get
their instruments back so quickly. On the second occasion, the technician
had to repeat the procedure a second time, but the customer was still
What Am I Saying?
Now you are probably
thinking, “Hey, I thought you were going to talk about using UV to build
up the shell?” Well, I couldn’t resist the chance to demonstrate how happy
these customers were to have their hearing aids repaired so quickly. Now I
am going to tell you how using UV for the same process would have made
them, and the technician, even happier.
Its All About Saving Time
Remember how the
technician had to apply the polish, and then wait 10 minutes for it to
dry? And how he had to do this 3 times? (Twice for the second customer).
That’s 30 minutes of his (and his customers) time. What if he could have
achieved this in less than 1 minute each? And what if this same process
happens over and over again, how much time will that save?
How to Apply Hard Finish UV Lacquer
UV hard-finish Lacquers, such as Fotoplast/Lacquer, is supplied in a
bottle with an application brush. It has the viscosity of something a
little thicker than water so it is very easy to work with. It can be used
on any type of hard shell, is completely hypoallergenic, and can be buffed
down if too thick. To apply, simply brush on the shell in the desired
location for build-up, and hold next to a UV light source. A 2 lamp
fluorescent model such as the Dual-Lite or UV9W-2 works excellent for
this. Spot cure guns can also be used, and though it is overkill for this
procedure will cure very rapidly. The lacquer will start to harden
immediately after exposure, and depending on the thickness of the coating
and how close it is to the lamps, will be cured in under 60 seconds. The
lacquer leaves a shiny coat and usually requires no buffing. The two
things you need to keep away from during application are the faceplate and
any trimpots that may be mounted in the shell. Any materials applied to
these areas will create a cosmetic problem, as well as freeze any trimpots
in their current locations. Like anything you apply, be careful.
Now, you don’t need to hold the unit between your
fingers until it is cured. Once the outside layer has hardened (which is
just a few seconds), just place the unit on the tray under the lamps for
the remainder of the cure time. If you really want some help holding the
unit, the Lite-Isserie Turning Unit can hold the hearing aid under the
lamps and rotate it so it cures evenly. And you don’t have to worry about
leaving the unit under the lamps for too long. You can’t over-cure this
type of material, so no harm done.
How to Apply Soft Coat UV Lacquer
Sometimes you need a little more than a hard coating can give you.
Sealing or slippage problems may require a soft coat which will be more
likely to mesh with the ear canal. Fotosoft/Lacquer is an excellent
material for this type of application. It also is supplied in a bottle
with application brush and has a thicker consistency than the hard
lacquer. To apply, simply brush on, trying to form a thin seal around the
circumference of the canal. And just like anything else you may apply, try
not to get any of this on the faceplate or in any trimpots that may be
mounted in the shell.
Where the soft coating is a thicker material, it is
going to take longer to cure. Depending on your equipment, the thickness
of the coating, and how close the hearing aid is to the lamps, it could
take 5 minutes or more to completely cure. And to make sure it cures
evenly you should use a Lite-Issreie Turning Unit to rotate the hearing
aid under the lamps.
Some soft coat materials will produce a sticky
residue on the surface of the material after it has cured. And no matter
how long you leave the unit under the lamps this tacky residue is still
present. This is called the “smear layer” and is due to oxidation which
happens during the cure process. This residue can easily be removed with
an alcohol wipe or Tech-Care Wipe. It is typically present when curing
Part Two will look into repairing cracks and holes in the shell.
UV Safety Glasses
Have you checked out our Factory
2nds? These are brand new pieces of equipment which have a cosmetic
imperfection or two, but work perfectly fine. Check out our
Factory 2nd page to learn more.