Scrolling overhead projector transparencies - experiences?

Factual Questions
1

Someone here is bound to have some experience - I can’t find any commentary elsewhere…

I sometimes teach in a classroom with an overhead projector and a stack of blank 8-1/2 x 11 transparencies. After each class I laboriously clean off each film with water, but it still makes a mess of me and everything around me.

Plus, the films are smaller than the projector panel, so a lot of “area” gets wasted.

It occured to me that an improvement would be to mount a roll of full-width film on the front of the projector and have it feed a take-up reel at the back, then just swab it with a sponge when the roll runs out and you’re rewinding.

I went to the 3M (projector manufacturer) web site and what do you know, they had exactly what I was looking for as an attachment for their machines.

Are they the cat’s pajamas? Anyone know?

2

Liquid from the sponge can inadvertantly get rolled up in with the just cleaned film. It won’t evaporate in there. This can cause ickiness.

3

Wow. I haven’t seen roll-fed OH projector film in 25 years. More accurately, I haven’t seen the stuff actually used in about 30 years, but our projectors had the brackets for it.

You’d need to re-wind it back in screen-sized bits - wash and dry, roll it in, wash and dry, roll it in, lather, rinse, repeat.

You may have better results with dry-erase pens, as they’d just need scrubbing off with a towel or a whiteboard eraser as you rewind the roll.

4

This is exactly what was used in all the lecture halls at my alma mater. Even the smallest classrooms had a pair of overhead projectors, while the largest had four of them projected on large screens. I think the professors used grease pencils and would roll the transparency during the lecture. (We used to wonder who had the job of cleaning all of those rolls.)

5

Yeah, I have to get the sheet film bone dry before I can stack it. I figured I could rig up a multi-fingered squeegee with three or four dry towels after a wet leading edge, but I’m worried that it really also needs a few moments to air dry, as gotpasswords indicates.

The rolls have 100 feet of film on them, so I’m hoping it’s practical to use the whole roll before the clean/rewind step, but I’m concerned that the wet-erase marker ink might start to bond if it sits too long uncleaned.

I’ll have to experiment with dry-erase markers and grease pencils.

6

I used one and left it until the end of the roll and didn’t have a problem with it getting messed up.

I used to have my students clean it but they were in 7th grade and thought it was fun for some reason. I don’t know what age you teach though.