Insulation tape on top of vintage coils

Here is a Q for the old timers amongst you.
What is the material used as the final insulation layer on all those old radio and telecom coils. It looks like a cotten cloth fabric (very fine) and is usually black or umber or orange. Often with a shiny varnish or wax impregnated finish. When you peel it back it has a stiff card like feel to it. Was it actually a cotton based material?
I'm getting interested in reproducing old coils and just wondered if this tape covering is still available?

[quote author="everett"]it. Was it actually a cotton based material?
[/quote]
Silk - usualy said, but dont know exactly what material,
they are (and was) many techniques how chemicaly refine (raffine) celuose. Some production name name is viscose. and it is cotton/wood/or every other source based.

xvlk

[quote author="xvlk"][quote author="everett"]it. Was it actually a cotton based material?
[/quote]
Silk - usualy said, but dont know exactly what material,
they are (and was) many techniques how chemicaly refine (raffine) celuose. Some production name name is viscose. and it is cotton/wood/or every other source based.

xvlk[/quote]
cellulose is the basics of early acrylics in the 20's - the first plastics and forms the basis of the modern 3M plastic tapes. I may not know the exact product but I can tell you just by looking at this material that is not cellulose or viscose. A silk or cotton base is likely I can go along with that but in reality this still doesn't tell me what the material is or whether I can ggt it. Any way thanks for trying.

Nowdays, everybody uses glass tape. 3M still makes many models, mostly classed by tempeture, then insulation breakdown. It's a cloth and fiberglass composition, usually bought in 1/2 inch or bigger thicknesses. Sometimes you can find a substitute at the local drug store. 3/4 is very popular back then. The color was whatever they used to process the transformer, varnish, varnish with red food coloring (Neve output), black epoxy paint, airdry epoxy, black potting compound, etc.

Brown paper wrappers are just KP, or kraft paper, or butcher paper.
Usually 20 0r 30 mil.

[quote author="CJ"]Nowdays, everybody uses glass tape. 3M still makes many models, mostly classed by tempeture, then insulation breakdown. It's a cloth and fiberglass composition, usually bought in 1/2 inch or bigger thicknesses. Sometimes you can find a substitute at the local drug store. 3/4 is very popular back then. The color was whatever they used to process the transformer, varnish, varnish with red food coloring (Neve output), black epoxy paint, airdry epoxy, black potting compound, etc.

Brown paper wrappers are just KP, or kraft paper, or butcher paper.
Usually 20 0r 30 mil.[/quote]

Thanks cj. Good info there.
My research on this entire subject (trying to find a DIY antique coil insulation tape methodology), that closely follows the look of the original has now been narrowed down and FWIW I will share it with the rest of the group. Bear in mind that the methodology is NOT to achieve the best modern insulation/electrical property. The aim was to SIMULATE the look of an old antique coil restoration because of the antique value of the original equipment.
The tape used as the final layer of the coil is white surgical adhesive dressing tape. Depending on the brand purchased this will be a silk or silk like ester based fabric. It is cut and dressed and applied round the coil no more than two layers thick.
This fabric is now dye colored with a modelling paint brush very lightly using a water based paint. Do not use too much water as the tape is somewhat water resistant and too much liquid will just make a mess as the paint will run all over. Use just enough water to allow the brush to take up the solid paint pigment. Once the color density has been reached and the white is no longer showing place the coil on one side for 48 hours and let the tape thouroughly dry.
Once the tape has dried, do not touch it as the paint will rub off and you'll spoil the look. Now get some CLEAR Gyptol varnish and quickly light coat with a brush around the tape surface. Place once again on one side and let the coil dry for 12 hours.
Finally lightly rub the varnish with 000 grade steel wool to take the shine down and age-dull the surface.
You will now have an antique coil that looks like the original insulation treatment of the 1930's. In fact this also simulates the modern Gyptol Cotton Adhesive Insulating tape that is VERY hard to source outside bulk manufacturing OEM operations. Glyptol clear varnish is itself hard to source but no where near as difficult as Glyptol Cotton fabric insulation coil tape.
If anyone wants a source for the clear (and red) Glyptol (mail order) I can provide it.
If any one is wondering, the treatment does provide an electrical age resistant insulation and is definitely more than just a cosmetic treatment.