Typewriter Talk / Backing sheets

**Posted by TypewriterKing** 08-4-2016 17:58:22

I know this sounds pedestrian, but for many years, I have always had at least one extra sheet of copy paper everytime I used a typewriter. On occasions, I've used two. I have never heard of backing sheet material like this before, but it sounds like a very neat idea. I put two or three sheets in all my typing because I want to protect the platen and the type bar faces as best I can.

**Posted by Spazmelda** 08-4-2016 18:14:11

Beak a mil is sort of an archaic measurement. I've only ever seen it for thicknesses of paper and sheeting. It is a thousandth of an inch. So 10 mil 0.01" or 0.25 mm.

**Posted by Spazmelda** 08-4-2016 18:29:57

Oh, but I missed the main point of what you were asking. So yes, I measure my 24 lb HP laserjet paper at about 0.003" or 3 mil. So, the 10 mil Allied backing sheet would essentially be the thickness of 3 of those sheets of paper (plus a little more). And the 5 mil would be just a little under the thickness of two sheets of that paper used as backing. However... the mylar seems to be a bit different than using just paper as a backer. It is sturdier. For example, when you use paper as the backing sheet, you almost always see impressions of the letters in at least the 1st backing sheet. With the mylar, you do not.

Reading a couple of other patents for backing sheets (I was bored today) I came across the idea of taking a legal size paper to put behind the backing sheet of mylar and folding it over the top. Then insert your typing paper into the fold, similar to how they would do when they would sometimes do manifolding for carbon copies. This made winding the paper in very easy and it required no straightening. The patent I was reading claimed that the paper behind the backing sheet (in that case, celluloid) prevented the backing sheet from slipping on the platen. I have not noticed the mylar slipping, even using the shiny stuff. I don't know how mylar is different from celluloid?

Anyway... I know it's sort of overkill, but I can use the leftover mylar in my cricut now to cut stencils.

**Posted by malole** 13-4-2016 04:22:04

I ordered some of the 5 mil, shiny both sides as I couldn't find any matt, but it works really well, doesn't seem to slip, and even my hardest platens are improved. I never would have thought of this myself, thank you!

**Posted by Spazmelda** 13-4-2016 05:11:01

Oh good! I'm glad it worked for you. I tested it on a bunch of machines and it seemed to improve the impressions, but I didn't know how objective I was being.

I remember the thread where we were all discussing this and we couldn't really come up with a suitable material to try. I don't know if mylar is different from 'celluloid' which is what the old ones were made of, but it seems to be a good solution.

**Posted by KatLondon** 13-4-2016 05:19:29

I'm with Beak! Horribly confused. So 10 mil = .25mm. I think 'mil' must be only in the US, everywhere else is more or less metric and unfortunately, 'mil' is how most people pronounce mm! Thanks for the explanation Spazmelda, I was trying to work out how something the thickness of a chopping board was going to go through my rollers!

But I'm all for the backing sheets idea.

**Posted by Spazmelda** 13-4-2016 05:36:12

Right, it is pretty much a US measurement, and not even used much here as far as I can tell. I think the use of it in describing thickness of sheeting is just a weird hold over. It would make so much more sense to use metric measurements, but that's the US for you. While looking for proper thicknesses of materials, I did run into situations where there was some confusion due to this measurement. For example, a seller on ebay would this the thickness as mm when it was clearly supposed to be mil.

**Posted by beak** 13-4-2016 09:05:32

I guess there will still be confusions as the USA gets more and more familiar with SI (metric) measurement. One thing that helps a good deal is to stick rigidly to the established abbreviations;

millimetre = mm
metre = m (and never M, which stands for mile)
kilometre = km (never KM)
kilogramme = kg (never KG)
and so on.

I think 'mil' is more likely to be interpreted as millilitre by the rest of the world - not including Liberia and Myanmar of course; your only fellows left who are non-metric. - that's quite a small club!

You have some time yet; there are still plenty of folk around who know that a six-foot girl is taller than average, and that an eighteen-inch platen is a big one, but before much longer the rest of the globe may not really understand you.

**Posted by KatLondon** 13-4-2016 10:09:08

Mils, yes, sounds like liquid, but in context... I was just imagining the biggest knitting needles I've got!
Anyway I will be checking out this backing sheet idea - if what people say is true, it might even render my SG1 usable.

**Posted by Spazmelda** 13-4-2016 13:00:11

Being a scientist, I am very familiar with metric, and I prefer it. If we had switched over in the 70s as we were supposed to have, everyone would know how much easier it is, lol. I used to have students complain to me about how hard metric was, well, yes when you are trying to convert inches to cm, or quarts to liters. But if you are all metric, it is so much easier!