OT: Cleaning video head on my Betamax VCR

[Steve Underwood]

Thompson Freeman wrote:
> On 08/10/2008 02:44:05 AM, Tim wrote:
>   
>> On Sat, 2008-08-09 at 21:20 -0400, Matthew Saltzman wrote:
>>     
>>> *Denatured* alcohol!
>>>       
>> Yes.  For those unfamiliar with the term, the usual cleaning alcohols
>> that you can buy are deliberately *poisoned* to stop people drinking
>> them (go figure!).  I had to convince the local pharmacist to give me
>> some untainted alcohol at one stage.  Later on, I had an even hard
>> time
>> convincing customs and excise to let me buy pure alcohol.  They only
>> relented after telling them about how poisonous and dangerous the
>> alternatives were.
>>
>> That tainting is bad news for cleaning video and audio heads.  They
>> can
>> be used, if you're desperate, and you wipe things clean and dry,
>> instead
>> of just letting them evaporate.  They contain a variety of things 
>> that
>> you don't want left behind on the heads, and that's very easy to do.
>> You're much better off finding something more appropriate.
>>
>> Be especially careful cleaning anything plastic or rubber, solvents
>> can
>> destroy them.  Remember that on the audio heads, at least, the head
>> block unit might have the magnetic part of the head embedded in a
>> plastic material.
>>
>> Do NOT use turps.
>>     
> <<snip>>
>
> I'm having a devil of a time following this thread with respect to the 
> solvent. Not that I'm about to clean any betamax heads, or any magnetic 
> tape heads soon, but with a background in chemistry...
>
> Apparently, we also have some challenges with having different 
> countries represented here, which also changes the underlying terms 
> some. Note that I quickly checked the Wikipedia for reorientation.
>
> Denatured alcohol is ethanol (the drinking type of alcohol) which is 
> mixed with something to make it unpalatable to poisonous to drink. If 
> memory serves, there are something like 200 additives approved for this 
> purpose, ranging from methanol (wood alcohol) through aviation gas to 
> some dyes. 
>
> Rubbing alcohol was originally something like 70% (vol) ethanol plus or 
> minus a good bit. In commerce, however, you are just as likely to find 
> isopropyl alcohol as ethanol sold as rubbing alcohol. Since isopropyl 
> is toxic, it is more likely to be a fairly simple solution of isopropyl 
> alcohol and water. Here in the States, you can find the isopropyl 
> rubbing alcohol at 90%, sold as an antiseptic. The bottle label I have 
> indicates, but does not explicitely state, that the product contains 
> only the alcohol and water. I don't know conditions 
> elsewhere.
>
> As solvents, it is my impression that isopropyl alcohol and ethanol are 
> very similar. As such, I'm curious if the video engineers have tried 
> it.
>   
In the heyday of tape, the liquid sold as tape head and guide cleaner 
was normally high purity isopropanol. I don't know if this is a better 
or worse cleaner than any other form of alcohol, but it was the standard 
material for many years. Some other cleaners can attack certain 
plastics, but isopropanol is pretty innocuous. Its rare to find any 
material it will damage. It was also used as a stylus cleaner for LP 
record players, and various other media cleaning jobs.

Regards,
Steve