Masking Slides for Projection

I've been doing some copystand work, photographing images out of books to use in the classroom. Most are fine to project as shot but some of the slides have areas I would like to cover up. When copying a square image I end up with parts of the copystand base showing at either end which detracts from the image when projected.
I have some old Letraset tape that I've used in the past but it occurred to me that the brains trust here might know of some better options. Cheap & easy to find is preferable.

Usually I would use silver polyester tape for this purpose. I'm not sure how commonly available it is these days, but large photo dealers like B&H sell it. Art supply shops might have it too.

There is a tape made by lineco, called Frame Sealing Tape. It is pealable, grey in colour, but is aluminium when pealed.

It is acid free and buffered to P.H 8.5. with 3% calcium carbonate. I am told that apart from its regular use, it is fantastic to use for masking slides, as it has a perfect straight edge to it (being foil) and will be kind to your slides as well.

The products number is L387-0151. It is 1 1/4 inch X 1000 inch and is made by Lineco inc.

I hope this helps

Stoo

I also used silver tape. I would remove the trans from the mount, tape it then remount the slide.

Hi,

I tried silver polyester tape at great cost but found the opacity wasn't all I'd hoped it would be. I then used a method suggested by Margaret Salisbury at an RPS event. This involved taking a piece of aluminium foil (kitchen type is fine, although chocolate bar is thinner plus you get to eat the chocolate!), folding it in half to give a straight and flawless edge and then attaching it with a heat-resisting tape (polyester or cine editing tape worked for me). It can be fiddly and involves the dismantling of transparencies (have some new mounts to hand), but I found the results far better than the tape I bought that was intended for the purpose.

Regardless of the actual method used, I think there is a lot to be gained in a slide presentation by changing the aspect ratio of slides from the usual 2:3 and thus putting rather more effort into the composition than is usually done.

Best wishes,

Steve

I like that creative thinking. I eat a square of chocolate every morning (Valrhona Guanaja) so it's easy to keep the foil.
I'm mostly wanting to fix some slides where I was copying square format photos. They never come out well on an uncropped 35mm slide. There are bits of the copystand at either end.