Tissue making – curl up and dye

Ok, sorry – inappropriate title again. Evidently, no dye is involved in carbon transfer tissue making. As far as I know, any attempt to add dye to tissue will cause staining of porous final supports, so it’s really pigments all the way. But the reference to the Blues Brothers movie was just too good to pass. Besides, the ‘curl up’ part is pretty accurate! Anyway, here’s part two of the blog I did earlier on making carbon transfer glop. With all the bubbles gone, it’s time to turn glop into tissue!

To put it into context, very briefly: tissue is in a way the black (or color) of the carbon transfer print (the white being the final support base, typically paper), and is a gelatin matrix with pigment embedded into it. To help in processing, we added sugar and glycerin. Sugar to help the tissue soak up water in the transfer bath, glycerin to keep the tissue from drying out too much and becoming too difficult to straighten for exposure. In the previous installment, we made the mix of gelatin, sugar, glycerin and India ink as the pigment, all dissolved in water. So we now have some jars of what looks like black-hole material simmering away at our SMD soldering hot plate. What’s next?

Our glop on the hot plate. It’s not outgassed, so you have to visualize it without the ring of foamy bubbles around the surface!

We now need to somehow spread this all out onto a suitable temporary support material, in a useful size and at a useful thickness. This requires a little explanation, starting with the support material. As far as I know, pretty much anything will work as long as it can be made reasonably flat, so it fits into an exposure frame, and as long as a gelatin emulsion will stick to it to a decent degree. The latter excludes a number of things; for instance, I’ve had pretty bad luck with sheets of what I believe was untreated polyprolylene (but maybe it did have some kind of coating or surface treatment to it), and I also walked into a roll of Melinex the other day that happens to be coated on two sides with silicone. Too bad, because nothing will stick to that stuff, ever. That will probably make it useful for something else, so I’ll hang onto it.

That still leaves us with ample possibilities. You could use pretty much any kind of paper, or, as I’ve been doing since recently, something like Yupo. Concerning paper: the main drawbacks to it in my opinion are its tendency to shed fibers if you warm it up and make it wet – which is exactly what happens when pouring warm, wet glop onto it. If you then start spreading out the glop, it’s easy to dislodge paper fibers that end up in the emulsion. Doesn’t have to be the end of the world, but it’s nicer to prevent it. I’ve had better luck (excellent, in fact) with a roll of fogged RA4 paper I was gifted some time back. Not being useful for color photography anymore, I kept it around and it turned out to be *just perfect* for a temporary support tissue. It’s basically RC (resin-coated) paper with a thin gelatin emulsion, and it turns out it behaves just perfectly in this application. It takes the carbon tissue well, dries fairly easily, withstands hot water processing and it even allows for reuse of the material. Excellent! One small problem – the roll I have is only 15cm wide. So no possibility of using it for 8×10 tissue…

Experimental tissue supports. Plain 80gsm copier paper on the left, Epson generic glossy inkjet paper on the right

After hunting down suitable materials for a temporary support, I didn’t come up with all that much. Paper of various sorts didn’t appeal that much to me, although previously I used to use a drawing paper from Schut, but the thing with the fibers…I even tried plain 80gsm copier paper, which worked surprisingly well. That is to say, it worked, and without entirely disintegrating during hot water bath development, but (1) I had to be quite careful when processing it as it’s just very, very fragile and flimsy and (2) it curls in very complex and inconvenient ways. It’s also (3) incredibly absorbent, which means some of the glop soaks right into and through the paper support, leaving a gelatin-and-ink stain on the surface the tissue is poured and/or dried on. It’s dirt cheap, it has that going for it. Not reusable, evidently.

Edge of tissue on plain 80gsm copier paper. Note how its absorbency makes for fractal-like edges where the glop has made its way through the fiber matrix of the paper itself. Cool effect! Otherwise not of any practical use.

And then, there’s inkjet paper. This is also a mixed bag, in my experience. I’ve tried it several times over the years, and the stuff that looks and feels like RC paper (I’ve got some Epson brand that looks just like B&W RC paper sans the emulsion) sort of works. But…inkjet paper often/usually/sometimes (?) comes with a microporous surface – at least, in my experience it usually does. For its intended purpose, this is great. A microporous surface, essentially millions of tiny holes, easily accepts ink and dries fast. But when you pour glop onto it, this results in a bit of a challenge. The air trapped in each of the pores expands as the heated glop touches it, so the air expands, forms a bubble and rises upwards into or through the glop, creating millions of tiny pinholes in the emulsion. This can be remedied fairly easily by wetting the inkjet paper and squeegeeing it immediately before pouring the tissue onto it. But wait a minute too long and the pores have dried out and you’re looking at galaxies in your tissue again. In principle it works, and the more resilient paper like the Epson RC stuff I tried is even reusable. The microporous bit isn’t ideal, though.

Cue the Yupo. Mentions of this material manufactured by the offspring of an apparently happy marriage of Mitsubishi Chemical Corporation and Oji Paper Co. Ltd (dating back to 1969, the summer of love – far out, maaaan!) for use in carbon printing go back as far as I can remember. Which, granted, isn’t all that long, but at least a couple of years. Suffice to say, many people have loved it in this role, and having tried it, I can see why. It really has just about all the benefits of RA4 paper I mentioned above – and in fact, it’s somewhat similar in terms of being a synthetic material. It doesn’t have a gelatin coating on one side, but instead, both sides are covered with a very thin film of a polymer that somehow easily bonds to lots of things. This makes it easy to paint, write and mess about on, and it also takes a gelatin emulsion very well. If you like a very clean look to your prints, you can even use it as a final support paper. A print transfers to it very easily indeed. I don’t particularly care for its super-smooth character, but for some images, perhaps it works.

So, long story still pretty long – I bought a big-ass pack of Yupo, without ever having actually touched the stuff before, and gave it a try. Yupo comes in various types, and mine just so happens to be called Superyupo FEB200, which stands for a 200 micron thickness and a weight of 158gsm. It works a treat, I must say. Why did I take a gamble on a 125 sheet pack? Well, I searched a bit on online shops and while most tend to offer silly quantities like 10 sheets of A4 at insane prices (in my opinion…), this shop aimed more at printing professionals at least had a decent price per square meter, provided you buy a decent quantity from them. No problem there; I can’t imagine a pack of Yupo going to waste one way or the other. Worst case scenario, my girlfriend ends up with a massive quantity of spare sheets for her Bambook, which as far as I can tell is a particularly cunning way of selling Yupo at a pretty steep price uplift. I digress…

Yupo FEB200, cut to a convenient size for 8×10″ tissue, with 8×10″ negative size marked out in ballpoint

Turns out that if you cut a 45x64cm sheet of Yupo (that’s the size I got) into 6 equal parts, the resulting sheet size pretty nicely fits an 8×10″ tissue. Alright, the narrow side is a bit on the narrow side, so to say, but it fits. And no losses, that’s nice. I hate losses. I found that if I mark the actual size of an 8×10″ negative onto the Yupo in ballpoint, it really helps me to pour the right tissue size. If I don’t do this, I usually end up having too wide margins to the side and end up with tissues that are slightly too narrow, or with corners that don’t reach the corners of the negative. Simple problems ask for simple solutions.

An important property of a temporary support tissue is that it lies absolutely flat as you pour the glop onto it. Glop is warm, and some supports tend to curl under the temperature differential, creating problems with even coverage. I also found that Yupo doesn’t always get through the tissue-making and tissue-using process entirely unscathed. It’s pretty dimensionally stable, but not perfectly so, and it does crease, fold etc. Running a clothes iron across it at its lowest setting takes the worst folds and creases out of it if I reuse it. I also find it’s necessary to stick the Yupo to the surface I use to pour the tissue. This is easily done by wetting the underside of each sheet and simply sticking it to the countertop. Wipe across the surface with a dry finger to move any trapped air from underneath it and it stays put quite nicely.

Mist some water onto the bottom-side of the temporary support sheet (here Yupo) and paste it onto the countertop; it’ll lie nice and flat this way
Yupo assembled for one batch of tissue pouring

Having prepared everything, the tissue-making proper can begin. It’s straightforward, really: pour some glop onto a sheet, spread it out so that it covers the required area, let set and allow to dry. The bit about covering the required area requires a little explanation. I used to use the trick with magnetic signage material to create a fixed border / tray in which the glop would pool, as described on e.g. the seminal Unblinking Eye article on carbon transfer (about halfway down the page). This has the obvious disadvantage that (1) you need as many magnetic borders as you’re going to pour tissues in one go, and (2) the area on which the pouring is done needs to be ferromagnetic. The former is a minor inconvenience, the latter is slightly more unfortunate as I prefer not to lug around too many sheets of plate metal in my darkroom. Nothing wrong with it per se, but it’s one more (big, unwieldy) item to keep around.

The other option for pouring is to simply pour the glop, spread it out and let the surface tension and viscosity of the glop do the work. And that works just fine. It takes a little elementary calculus to estimate a good amount of glop to pour and some finetuning based on initial results. It turns out that wet glop tends to pool at a wet height of about 1mm, so coating a surface area of around 22x30cm (the approximate size I tend to coat) will require 22 x 30 x 0.1 = 66ml of glop. Turns out that roughly 60ml usually does it for me. If the edges or corners retract too much after spreading it out, and this is not caused by flatness issues of the surface, then use a little more glop for the next pour.

Those borosilicate glass beakers are really nice. I like to use them for pouring tissue as well. 60ml nicely covers an 8×10″ area with some margin.

Pouring is easy; I just gently pour the entire amount for one sheet roughly in its center, where it pools nicely without running amok too rapidly.

The actual pouring. This is what it’s all about. The culmination of human existence and ingenuity.

And now comes the super secret element, the only tool that can be used if you want to be a Veritable Tissue Maker (VTM): the comb. Honestly, I used to just use my fingers to spread around the glop so it covered the intended area, and that worked mostly fine. The only drawback is that when releasing a finger from the wet glop, sometimes a bubble tends to form. A comb tends to leave no bubbles, and also allows for making fairly neat, straight edges. I got a 2-pack for something like € 2.00, so check with your local bank branch to verify you can shoulder the investment.

I think the cashier figured that I didn’t need this for my head.
Gently nudging a puddle of black liquid towards the edge of the Yupo – and preferably not over it!

Alright, I did do one modification to the bog standard combs I purchased. Turns out that due injection molding leaves some sharp edges to the teeth. When spreading the glop around, the sharp teeth may catch in the surface of the temporary support and scratch it. I had some issues with this when pouring onto RA4 paper, with small slivers of its emulsion actually being scraped off and remaining stuck in the tissue. I even had some end up embedded in a print. Not good. Simple solution, once again: gently sand down the tips of the teeth so they’re smoother. It’s the little things in life, eh!?

There it is, only takes a couple of minutes, but it’s a veritable work of art that rivals those of Anish Kapoor!

After spreading around some smooth, black gunk, the waiting game begins. For some reason, tissue pouring day ends up being a particularly hot day, and this time was no exception. The whole thing really is quicker if it’s not 32C in the room you’re working in. It takes quite some time for the gelatin to set at such a high temperature. In cooler weather, it’s possible to move around the freshly poured tissues after just a few minutes; I now had to wait for half an hour or more before I could move batch 1 to a different place to make room for batch 2!

2 batches of poured tissue waiting to be hung from a line for further drying

Previously when I did carbon transfer, i.e. a few years ago, tissue making used to be a somewhat messy and also stressful process, as I recall. I fussed a lot about dust settling on the fresh tissue (turns out it’s not really that much of an issue if it happens), I was somehow always out of room to put them after pouring, it took long for them to dry, etc. I guess it was a combination of a less organized darkroom than I have now in our new home, part mindset, part experience and part a bag of tricks that always expands and makes life easier. The one major improvement has been the use of the hot plate shown at the start of this post. Because I can now keep the glop warm while the outside of its containers remains dry, I somehow have a lot less trouble with drops of water all over the place, having to wipe my hands continuously (the comb trick also really helps) and overall the entire experience is much quicker and easier. It really is the little things that make a difference!

After letting the tissues set completely, I hang them to dry. Depending on the weather, they take 24-48 hours to dry completely.

Once dry, the tissue do tend to curl up a bit, even with a little glycerin in the glop. Not to worry: as soon as they are completely dry, I stack them and store them under a suitable weight or in a folder that keeps them flat.

I guess I now have to start printing again…although there are a few other darkroom chores waiting for me that have priority over more carbon transfer.

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