Having trouble getting tape to stick when indexing

Justin W · Post by **Justin W** » Mon May 18, 2009 4:32 pm

Howdy all!

Well, I'm shooting on flexible film now (VRP-M 4x5), and liking the versatility of a cut-able, size-able film that I can mount well way from the edges of glass, leaving me room to avoid shadows from film holders, among other benefits... It's also much less expensive.

I've opted to not sandwich the film between sheets of glass because I never want to see what woodgrain looks like.

The technique I've employed thus far has been to tape the film to a clean sheet of glass with Scotch clear tape. A layer of mineral spirits between the film and glass has worked nicely as an index-matching fluid.

The problem is that after a period of time, even as short as half an hour of settling time, the mineral spirits has been apparently breaking down the adhesive of the tape. I'll return to find the tape wrinkled and beginning to detach from the glass. This loss of seal around the edge has by then led to air pockets around the peripheria of the film.

Even water will unstick the tape. I am most interested in making a one-sheet-of-glass indexed mounting work for transmission masters that will stay properly mounted overnight or even for a few days while I copy it a bunch of times.

Is there a type of clear tape that will stand up to mineral spirits, or alternately, is there an index-matching fluid that won't take the stickiness out of Scotch tape?

Thanks, guys, for any help.

Hans · Post by **Hans** » Mon May 18, 2009 6:09 pm

I have been using lamp oil. It seems that the Scotch tape holds up well against it.

Justin W · Post by **Justin W** » Mon May 18, 2009 7:01 pm

Hi Hans,

Thank you for replying.
I'm curious about your technique. If I recall correctly, you posted some time ago a method wherein you taped two adjoining sides of the film down, then lifted the free corner, applied indexing fluid, then taped the remaining sides... I'm interested in trying the lamp oil as suggested, and have a few specific questions about taping with this method - how is it that you (if you don't mind revealing your secret) manage to not wind up with oil on the glass at the edge of the film on the un-taped sides that will inhibit the tape from adhering? When I visualize this, I cannot imagine a simple wipe with cloth or paper towel would not leave a skin of oil... Or will Scotch tape not be troubled at all by a film of oil on the surface to which it is to be stuck?

Also, have you found any method for dealing with the bubbles of air that is better than just getting them to migrate to the edges?
Thanks for your help, buddy.

Hans · Post by **Hans** » Tue May 19, 2009 11:22 am

When I visualize this, I cannot imagine a simple wipe with cloth or paper towel would not leave a skin of oil... Or will Scotch tape not be troubled at all by a film of oil on the surface to which it is to be stuck?

That's just what I did. I wiped it with a paper towel and then stuck tape over the remaining edges. But there was a problem here too. I found the method rather messy and it did not always work: If the film base was thick and had a lot of curl strength, sometimes very small air channels (where two pieces of tape joined) allowed air to be sucked in. Also, for Denisyuk exposures, I found the shadow caused by the tape very ugly.

A much better method was to use a washable childrens glue (made by pritt) to stick the film to the glass. For that purpose I used a laminator. I disconnected the heating element from the laminator.

Here is the procedure:
- Tape the film on one side to a piece of 2mm thick glass.
- Deposit a stripe of the glue where the film and glass meet.
- Very gently allow the film to hinge onto the glass.
- Put the glass onto a piece of paper. The paper must me larger than the glass so that it comes out of the laminator first.
- Gently rest another piece of paper on top of the glass. (The pieces of paper prevent glue from entering the laminator).
- Run this sandwich through the laminator.
- If the laminator struggles to run the glass through you can pull on the two paper sheets that first come out of the laminator.
- Let the sandwich rest for a few minutes and then pull the paper from the top of the lass. Start pulling from the side where the Scotch tape holds the one side of the film to the glass.

This method allows the film to be processed as if it were a glass plate. If you want to remove the film from the glass (when using the glue that I used), just warm it up with a hair drier. It will then just curl of the glass. Any remaining glue can be washed off with normal tap water.

HoloM · Post by **HoloM** » Sat Oct 03, 2009 7:45 pm

hans, could you tell us which glue from pritt it was? picture might be helpful.
thanks a lot. Did you try to put it on the gelantine side?

holo_cyware · Post by **holo_cyware** » Sun Oct 04, 2009 9:41 am

I've been told by a good holographist that http://www.3m.com/product/information/P ... esive.html and similar works well with film.

If you stick the film to a glass plate, it becomes a permanent mounting "thing" and the film can be processed "as it is". Care is needed to avoid air pockets. Obviously the gelatine should be outwards, and I'm wondering what will happen with double coated films in this case.

The_Stranger · Post by **The_Stranger** » Sun Oct 04, 2009 12:52 pm

HoloM wrote:hans, could you tell us which glue from pritt it was? picture might be helpful.
thanks a lot. Did you try to put it on the gelantine side?

I believe Hans has left the building so to speak, but I have been reading the vast archive of old posts for weeks now, and I found the following post from Hans regarding laminating film to glass:
http://holographyforum.org/phpBB2/viewt ... ilit=pritt

In it, he says:

The glue that I used is made by "Pritt" and is called: "Power Pritt". It is a transparent glue that is washable at 60C.

He also says:

Yes that is the one (the 35mg tube).
[...]
I laminated emulsion up because I was not sure if the glue would mess with the emulsion. It would be an interesting test to see if it also works emulsion down because the glue is water soluble at 60C.

He is refering to a link someone gave, but that link is not really pointing to anything anymore. A search of the pritt website gives this though:
http://www.prittworld.com/be-d/producte ... pritt.html
Allthough in Dutch, it shows a pritt tube with a 35gr content, washable at 60 degrees. It is also a type of pritt glue which is suited to glue glass (the "normal" pritt is not suited to glue glass).

So I believe this might be the glue he was talking of.

The international website had this product, same colourscheme, also for glueing glass:
http://www.prittproducts.com/products/d ... 1&plid=726

Might be the same product in a different packaging, but that glue is washable at 40 degrees, so it might be a bit different. (and isn't available in the mentioned 35gr tube)

Colin Kaminski · Post by **Colin Kaminski** » Tue Oct 06, 2009 12:21 am

I only use film for tests as I prefer to store plates. However some of the fine art holograms I own are made on film laminated to glass. The lamination is done with the emulsion facing out and the sandwich is treated like a plate. The set up I have seen is laminating a piece of film with a sheet of glue in a laminate. The same laminate can laminate a sheet of black plastic to the sandwich once the hologram is developed.

John Sonley · Post by **John Sonley** » Sat Nov 14, 2009 5:17 pm

Hans - I have printed off the advice you gave a few years ago regarding using Power Pritt to temporarily laminate Slavich film to glass using a laminator. As I've nearly run out of my old Agfa film I need to get 'up-to-speed' with this technique and I bought a very cheap Acco Rexel laminator Model LS 240 on eBay - I've disconnected the heater circuit but I'm having great difficulty in getting the laminator to accept 2mm glass alone - the electric motor stops. The specification for the laminator says a maximum thickness of 1mm
I guess there are two options:
1. find a source of 0.75mm glass - no joy so far!
2. dismantle the laminator and enlarge the holes supporting the bearings for the two rollers - it would be a bit 'hit and miss' but it might work

Do you have any other suggestion

BRgds
John

Sergio · Post by **Sergio** » Sat Nov 14, 2009 6:29 pm

John, does your laminator roller is supported by two springs that you can adjust?
You could also remove the aluminum heat plate, 1mm glass plates is possible to order within a glass slide microscope manufacturer.