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The Substrate Gum Printing Method


Introduction

This process is suitable for other handcoated processes besides gum. Basically it involves affixing the paper to an inert material with a built on registration system. The paper is later removed from the substrate.

These instructions are designed for those already familiar with the gum printing process. One should obtain any of the instructions available for traditional gum printing, and adapt this method to them. This is not meant to be a complete treatise on gum printing.

The benefits are:

Tools and materials needed:

*Register pins and tabs are available through most printing industry supply houses.

Figure 1.



Making the substrate register system

Note: These pins will stay put for a long time. I just found some substrates with pins on almost 20 years! Once this job is done, you won’t have to do it for a while. You may also find that by using a grinder with a fine wheel that by grinding down the round stub on the pins to lower it, will make it fit into a print frame better.

Mounting the paper

I like the Seal system used with their Seal 4000 drymount tissue. However, once you understand the principle involved here, you may work out your own system. You must also be very careful not to get any tissue transferred to the top of the paper.

Dry mount the paper to the area designated on the substrate. If you have trouble with the paper forming large bubble like pockets, you may have to press and dry the paper first. If the pins are affixed near the edge of the substrate, they can hang outboard of the dry mount press platens and not interfere with the mounting process.

When the paper is mounted it should look like Figure 1.

It should now look like Figure 2.

Figure 2.

By now you have probably gotten the point of all of this. What we have is registration system and a tamed piece of paper for gum or any other multi-coat printing process like gum over platinum, etc.

Modifications to the gum printing process

The gum printing process is the same as the traditional but with the following modifications and benefits.

Since you can coat quickly, develop quickly, and dry quickly. You can make many coats in a very short time. Your goal will be to build up the print in layers, adjusting the color and the contrast in steps.

Do this by:

Normally this creates the problem of the print washing off the paper, since in the traditional process, you can neither lay the print down to dry, because it will puddle and buckle, or hang it up, else the image will "slide" off the paper. With the substrate process, you can shake of the excess water, and dry quickly under a forced hot air blower. Only one side of the paper is wet which also shortens the drying time.

You may also dip the print into a hardening bath of alum or dilute Glyoxal before forced air-drying. The traditional formaldehyde is not recommended due to its extreme health hazard.

My development times are under 5 minutes and drying usually takes 1 to two minutes.

Everyone who has done the traditional gum process has seen the beautiful results of short exposure short development print, and then been helpless to prevent the image from sliding off the print. This is the normal way to work with this method. One can do up to 6 coats on a print in less than an hour. This would be stretching it a bit but I have seen students do it.

Some see the fine registration that one gets using this method as being the primary purpose of this system. This is not so. The registration is a benefit, but the real benefit is the ability to build a print in steps adjusting as you go, and the ability to use the short exposure-development system.

Exposure

You may find that the pins interfere with the glass in the print frame. This problem can be solved either: (1) by using a heavy piece of clear mylar over the print to shim it up to the height of the pins. (2) Grinding the pins down on a grinder. (3) using a sheet of heavy plate glass instead of a print frame (you're registered, so you can look to check progress if you are doing Ziatypes, etc.) and allowing the pins to sick out from the glass.

Removing the paper from the substrate

Place in a drymount press at about 200 Deg. F. (I stick in the paper part and let the pins hang out so that the press gets a more even pressure on the paper.) After about 2 minutes,

open the press, and with a pot holder hold one end of the board and peel up one edge of the paper and pull gently off the substrate. If you are doing large prints, it may cool off mid way into the removal process. If this happens, just insert in the press the remaining part and repeat.

You print will now have a glaze of stickum on the back. At this point I like to use the Seal Fusion mounting system, but any dry mounting system will work. I like to remount the print, after it is trimmed to the image area, on to a piece of the same paper it was made on. I had one student who had access to an etching press and she use a piece of plastic and made a platemark in the paper with the etching press and then mounted the print down in the platemark area and then overmatted it. This made an elegant presentation.

Notes:

Almost any inert material will work for substrates, just don't use any iron based metals if you plan to do platinum or palladium printing in the mix.

Some of my students liked to size between coats. This is quick and easy to do and I recommend it. Make up small pot of warm gelatin and keep it on a double boiler on a hotplate. Spread it on between coats with a foam brush and then dry with a hairdryer. I didn't find it necessary to harden it.

Dick Sullivan