George Murphy wrote to the effect that:
>...distilled water is ionically imbalanced.
and others argued it is not...the pH is 7.
Maybe under tightly controlled conditions the pH is 7, but the pH of pure
water changes in response to even trace impurities. I just took two
samples of water that has been treated by reverse osmosis and then
distilled slowly in a high quality hard glass still and the beginning pH
was about 9 (alkaline). As it sat, the pH dropped steadily to below 7
(slightly acidic). I assume the impurities are dissolved gases such as
CO2.
Even though the pH can change radically, it only involves a small number
of ions. If some buffering capacity is added, the pH becomes much more
stable, and I cannot imagine the water will threaten anyone's engine
block. Distilled water is no worse in this regard than tap water, and, as
someone pointed out, there is a tremendous advantage in not precipitating
out dissolved material on the inside of the radiator and engine.
It is probably true that pure distilled water will turn rusty if it is
used (alone) as a coolant. So would any water; rust inhibitors are needed.
I have been using a mixture of distilled water and antifreeze (usually
Prestone) for at least 25 years, in many cars, some of which have run to
very high mileages. It does not turn rusty, it does not make deposits on
the inside of the radiator, and I have seen absolutely no evidence of
corrosion.
************************************************
Dave Ahrendt asks about paint for an MG-TC.
Centari is, I believe, Dupont's trade name for acrylic enamel. Acrylic
lacquer is different. Acrylic enamel may be applied either with or
without added catalyst (hardener). The hardener greatly accelerates the
curing process, and increases the gloss of the paint. Acrylic lacquer
uses a relatively fast evaporating solvent, and air drys.
Both have advantages/disadvantages
Acrylic lacquer dries fast enough that it usually does not smooth out to a
particularly glossy surface (very slow drying thinners may improve flow
out, at the risk of causing runs). It usually must be color sanded and
buffed for a glossy finish. The finish is a bit softer than catalyzed
enamel. It is fairly easy to repair chips and scratches, which is good
because you will get a lot of them. The finish, after polishing, usually
resembles the original finish. Acrylic lacquer is an excellent choice for
do-it-yourself refinishing in the driveway, because fast drying reduces
runs and collection of dirt, ease of touching up makes it easy to fix
mistakes, and it isn't particularly toxic.
Acrylic enamel with added catalyst or hardener cures to an extremely
glossy hard finish that is tough and durable. It looks a bit "plastic"
for my taste immediately after curing, as if the car were wet. It would
not look right (to me) on an MGTC; they were never that shiny.
Fortunately, catalyzed acrylic enamel can be color sanded and buffed like
lacquer, or just buffed with fine rubbing compound, and then I think it
looks fine--with a soft gloss combined with a durable finish. Enamel can
be used without the catalyst, but it cures more slowly and may be
difficult to repair. (Air-dried enamel can be "recoat sensitive" meaning
that a coat added later can lift previous coats. This is a major bummer;
the catalyst decreases this tendency).
I think either finish would be durable enough for a car that will not sit
out much. I decided on catalyzed enamel for my bugeye because the inside
of the bonnet, door sills, under fender surfaces, etc. will have very
little shine if done in lacquer, and it will be very difficult to buff
these surfaces to make them shine. Life is too short (for me) to buff an
engine compartment.
I could write much more on this subject, but won't unless people want me
to. If the car is to be driven, and you want it to look very nice with a
minimum of cost and effort, I would go with catalyzed enamel. Centari is
probably fine, or PPG. Prime with PPG DP40 or the grey equivalent (DP50??).
It is wonderful stuff. After the finish paint cures, buff the outer
surfaces with very fine rubbing compound if you want to get rid of the
"wet" look.
If you are going strictly for show, then all bets are off. You can even
get nitrocellulose lacquer for a real historic touch, if the car is going
to be wrapped in cotton wool most of the time.
Someone mentioned Imron; I'm not real sure what "Imron" is; I thought it
was a brand of catalyzed enamel. It is presumably super paint, but color
choices may be limited. Any professional painters in the group?
Ray Gibbons
|