Solvents for Tape Residue - an opinion

Bill Finch (alioth at ix netcom com)
Mon, 05 Jun 2000

I use 91% isopropyl alcohol to clean the tape path. Let me explain why.

There are several requirements for selecting a satisfactory solvent for
cleaning the residues left behind by tape being transported through a
camcorder such as the TRV900.

1. The solvent must be able to dissolve and transport the tape residue
to a cleaning swab or cloth.

2. The solvent must not react with any of the parts of the tape
transport or any part of the cleaning cloth or swab.

3. The solvent must not leave a residue behind on the tape transport.

For the most part, alcohols and chlorinated and fluorinated hydrocarbons
have been used separately and in combination to satisfy these
requirements. Many other solvents would work but are generally
unavailable to the general public.
If you feel like a chemist you can visit the NCMS solvent database at:
Some transport manufacturers specify a solvent for cleaning. Some don't.
Some push their own brand of cleaning fluid, but this is generally out
of fashion because of environmental liability laws.

Over the past (I don't care to say how many) years I've cleaned tape
transports using manufacturer recommendations with the following
materials, separately and in combination:

a. Freon TF
b. Freon TMS
c. Dichlorofluoroethane
d. Perchloroethylene
e. Methyl Alcohol
f. Ethyl Alcohol
g. Isopropyl Alcohol
They all dissolve tape residue. Each have advantages and disadvantages.
Without expanding on these, and in the absence of a manufacturer
recommendation, I have learned to avoid solvents b through e above.

Also, since pure ethyl alcohol is taxed heavily I won't use it either.

This leaves Freon TF and Isopropyl Alcohol. Both materials clean well.
Freon TF evaporates much faster than isopropyl alcohol. The problem with
rapid evaporation is that it leaves residues behind before the cloth or
swab can collect them. This is easily remedied by multiple cleaning
cycles. The slower evaporation rate of isopropyl alcohol gives the
advantage that it (and the dissolved tape residue) is more easily
collected by the cleaning cloth or swab.

Thus my favorite general tape residue solvent is isopropyl alcohol. I
always use the azeotropic concentration of 91% alcohol for several
reasons. It is 91% alcohol and 9% water. The water and alcohol evaporate
at the same rate from the azeotrope leaving behind nothing. If one uses
concentrations below the azeotrope the faster evaporation of the alcohol
leaves the slower evaporating water behind.

So how can you find good 91% isopropyl alcohol. I buy 91% isopropyl
alcohol from Walgreens and Eckerd drugstores. It is sold for it's
topical antimicrobal properties - mostly for injections. I always read
the label to see that it is just alcohol (and 9% water). I always test
it by placing a sample on a clean cotton swab and smearing it on a clean
mirror. If it leaves no residue upon evaporation it's OK to use for tape
path cleaning. If you want to see what a residue looks like just dip
your finger in the alcohol and smear that on the mirror.

Anyway - that's what I do and it works well. I have the other materials
on hand and would consider using them if the alcohol didn't remove the
tape residue, but I've never run into that situation.

Three obvious words of caution - always let the tape path dry completely
before you put a tape in the camcorder - always keep the solvent out of
the bearing surfaces - always avoid direct contact with the head gap if
at all possible. Heads (drums) are very delicate and very expensive.

Also, don't confuse 91% isopropyl alcohol (about $5 per quart) with
rubbing alcohol (about $1 per quart). Rubbing alcohol contains God knows

So - that's my humble opinion about cleaning tape transports.


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