Widget Of The Week
Nattex Copper Forming Dental Outfit, 1960?
Here’s a gadget to get your teeth into, or
rather, get your (false) teeth out of, had you been around in the fifties and sixties.
At least that’s my best and only guess about what the Nattex Copper Forming
Dental Outfit was designed to do. So let’s begin with some certainties. It was
made in England by Cottrell & Company, located in London W1. The date of
manufacture is a little harder to gauge but the components inside the box
strongly suggest that it was made somewhere between the mid fifties and the
early sixties. Now for the big one, what on earth is it for?
I welcome clarification from anyone who
actually knows, or has used one of these things but at this point all I can say
for sure is that it is a variable mains-powered low voltage DC power supply,
presumably used for electroplating copper, in some process involved in the
manufacture of dentures. The power supply part isn’t in doubt but the only
evidence I have for the latter assumption, that it has something to do with
dentistry, is in the engraved label on the front panel. That and the three
terminals on the front, which look like they might be for connecting plating
bath electrodes; the meter, which shows current flow, and the variable control
that probably adjusts the speed of the process.
Web searches using combinations of keywords
including ‘Nattex’, ‘Cottrell & Company’, and ‘Copper Forming Dental’ drew
an almost complete blank. This is clearly a rare and very unusual piece of equipment and
it also suggests that Cottrell & Co disappeared or were taken over some time
ago. The one and only lead was a possible connection to a present day company called
Wrights Dental. The Cottrell name is linked with Wrights but
their website makes no mention of a past merger or takeover and at the time of
writing I am waiting to hear from them if there is any connection. Updates to
follow if they or anyone else responds.
The front panel controls include a
three-position range switch for the meter, labelled x10, x5 and x1. There’s an
on/off switch and indicator lamp for the mains supply and a knob connected to a
multi-turn variable resistor or rheostat that controls current flow. Inside the
case there are only three main components, a mains transformer, a finned Selenium
rectifier, and the heavy-duty rheostat. The Selenium rectifier was the key to
dating the device. They were commonplace in mains-powered electrical equipment
up until the early 1960s when they were replaced by silicon diodes; this was no
loss, believe me! Selenium rectifiers were evil things with a limited life, and
when they failed -- which was all the time -- they emitted a foul and
long-lasting smell. To be fair it did make finding some types of fault a lot
easier... The rectifier’s job is to convert the low voltage AC coming from the
transformer’s secondary winding into a DC voltage. After passing through the
rheostat, the voltage ends up on the output terminals on the front. You can’t
see it from the photos but that rheostat is quite a thing. Basically it’s an
insulated tube, covered in a winding of resistance wire. A screw-driven
contact, connected to the knob on the front panel, travels up and down the
tube, varying the resistance between the moving contact and two ends of the
winding as it goes.
And so to it’s most recent and only known
history, which began when it came into my possession, at a large Midlands
antique fair. I spotted it fairly soon after arrival but passed it by as it
looked a bit boring and there was bound to be many more interesting things to
buy. There weren’t, so I returned to the stall just before leaving and wasn’t
at all surprised to see it was still there. After a brief haggle the
stallholder, who, like me, had no idea what it was settled on £8.00. That was a
bit more than I wanted to pay but it had been a fairly quiet day and even if it
was a total write-off there might be some useful vintage parts inside the box.
The case paintwork was in a terrible state but
it responded well to a strip down, a good clean up and a quick respray with
some white car paint. Inside it was just a bit dusty. Although everything
appeared to be in good order there was no way I was going to connect it to the
mains. The wiring is a scary rats-nest and there are simply too many things that can go wrong; I’ve had my fair
share of mains jolts and a blown Selenium rectifier is not something I ever
want to smell again…
What Happened To It?
This is all conjecture but I assume that
Cottrell & Company of London W1 disappeared or was taken over 30
or 40 years ago as there is no record of the business or any of its products
anywhere on the web; at least none that I could find. Equally there’s nothing
about Nattax or Copper Forming, in relation to dentistry or denture
manufacture, so it seems likely that this was a short-lived fad in the world of false teeth fabrication or replaced by some other processes. It
is possible that this is the only one of its kind still in existence and in an ideal world it should be worth a great deal of money. Sadly that is rarely the case,
as least as far as weird old gadgets are concerned. So unless an eccentrically wealthy
collector of vintage dental apparatus wants to make me an offer, my valuation
of £10, is probably not far off the mark. To be brutally honest it is practically useless, however, I can see a way of making it
worth a few bob. Whilst I normally condemn the conversion of
vintage items into wacky retro table lamps, in this case I might make an
exception. It wouldn’t be too difficult to do and relatively easy to make the
modifications non-destructive and reversible – in case it does turn out to be a
valuable artefact. It should also be possible to give the knobs, switch and
indicator lamp something useful to do by incorporating a dimmer switch, and
maybe even get that meter moving again, turning dull-as-ditchwater dental into funky ornamental...
First Seen: 1960?
Original Price: £?
Value Today: £10 (0619)
Features: variable DC power
supply, selenium rectifier, rheostat, 0 – 100mA current meter, range switch, power on warning
Power req. 230VAC
260 x 168 x128 mm
Made (assembled) in: England
Hen's Teeth (10 rarest): 9