I decided to post on the vast topic of tape head cleaning. I get asked about it quite a bit when dealing with customers prized and cherished tape machines. In addition, I'm often asked by others who are just interested in cleaning the heads / tape paths of their own machines. So, here is the best response I can give within the confines of this article. Also, Keep in mind, that what I cover in this article is applicable to "most" metal surfaces found within the tape path. The rubber and plastic however, such as pinch rollers etc., should not be exposed to chemicals that can degrade them. Typically a little isopropyl alcohol on a swab to clean a pinch roller won't hurt it, however, You wouldn't want to soak it for long periods in alcohol or more "harsh" chemicals. Do Your research on "reconditioning / cleaning pinch roller rubber".
First, I am not an authority on chemistry by any means. I understand the nature, purpose and safe application of the chemicals I utilize in electronics work. There are two reasons right off the top for the above mentioned. (1) Health / Safety when working with various chemicals, which is an obvious one, and (2) the health of the equipment being serviced of course, a lot of which is highly collectible, rare and just flat out expensive and sometimes irreplaceable.
Therefore, on account of the responsibility and accountability I have regarding customers and their equipment, I subscribe to the following approach. Simply put, I work to factory specification or as close as possible based on available service info etc., when such data is available. Otherwise, one must rely on experience, and again, a basic understanding of what is being applied to a particular surface material, and what the "generally accepted" industry standards are, which will vary of course.
For more certainty regarding interactions between the chemicals I use and the various surfaces I apply them to, I feel that the manufacturer / factory service techs are in most cases wise sources to follow. I base my own process on research and experience backed data, which in this case deals with safe and effective head cleaning. As such, I completely stand behind such chemicals / solvents as 99% Isopropyl as well as Denatured / Ethyl Alcohol (most formulas of which are safe for application to heads and most of the metals that make up the tape path etc.) and which do a fine job removing most of Your typical “head crud”, from light to even some heavier accumulations, depending on what is present.
Now, when dealing with heavy accumulations, including degraded acetate base material / polyurethane binder materials, oxides (in other words, degraded tape material / sticky shed conditions) etc. I find that Acetone or even Denatured Alcohol (again depending on how bad the condition) are good choices to safely clean tape heads. The chemicals / solvents mentioned for the purpose of head cleaning DO NOT damage / delaminate the “pole pieces of tape heads or otherwise damage most metals in the tape path. Many manufacturers and longtime service techs that work (or have worked) “in the trenches” use the above mentioned in various mixtures at times, as well as without mixture / dilution.
Additionally, it is worth considering, that many manufacturers (if not most) have either employed, commissioned, or otherwise sought the advice of chemists (and other “experts”) on this topic. It comes down to knowing when to apply a particular chemical / solvent according to the task at hand, how much to apply, and to do so in a very controlled manner. I make it a point to either remove or mask off / protect other surfaces that could be negatively affected, such as certain plastics and painted surfaces etc.
Lastly, my own process with the above mentioned varies according to the condition of the heads / tape path I am servicing. It is another one of those vast topics filled with varying opinions based a lot on information that isn’t always backed by the research and experience of those who have manufactured and serviced such equipment on a daily basis for many years / decades. Additionally, application techniques are not covered in this article, just due to the fact that it is not possible to cover every aspect of this topic in one post. However, it's not "Rocket Science", and typically involves applying a particular solvent (i.e. alcohol etc.) to a swab (light to moderate amount, i.e. a few drops or so, depending on the condition of surface to be cleaned) and carefully wiping and repeating until clean and residue free, which includes not leaving any swab material behind etc.
So, in the end, for those who have an interest in this topic, it is a good idea to conduct smart research, refer to Material Safety Data Sheets (MSDS info) and find information concerning how a particular chemical might react with a particular surface when in doubt. Different techs develop different processes that work best for them. The information I provided is not the “be-all and end-all” of the topic, it’s what I trust based on a long history of what is widely and regularly utilized by “the experts”, as well as my own experience, of which does not include any negative results to date.