Blog: Making Things

Risograph Printing

2019-11-15 by TTTThis

From what I've learned (I met some people in their riso printing studio the other day and learned the process and made some test prints), what can be done on risograph can be done on the regular photo service store printers, so I don't know if riso is that valuable.

The guys at the studio make their money from medium-sized runs (between 50 and a thousand or two) because its most cost effective than a photo studio but less so than (i forget the word but the machines used for bigger print jobs).

one thing is you have to do runs with riso, generally of 50 or more.

riso printers look like regular photocopy printers. there are four color drums (pink, blue, yellow, black). only one drum is in the machine at a time. you do your run with that color, then swap the color drum and print that color on the same pages. sometimes the color from one drum is still there for the next pages, so it can leave bands of color across the print (unfortunately). also, the first prints are less evenly colored (and darker generally) than the ones that are printed later on. The prints dont line up exactly. they can be adjusted i guess, somewhat like a lithograph machine, but i think less exactly. so sometimes your colors wont be lined up.

to make other colors, two or more colors are mixed. the effect is good, though. Yellow and pink can make a bright, even orange.

The machine can add textures. There are two options. One is 'Screen tone' which is like dots like in Archie comics, and you can control the size of the dots (and spacing therefore) and the angle of the dots. The other option is 'grain touch' which is a patternless color fill that can look like charcoal rub when its not applied strongly.

The maximum size the machine can do is 11x17.

In order to prepare images to print, the images must be separated into the 4 colors (which each are saved as a greyscale image) to print. The four separate images are printed separately on the same page. One way to prepare these is to use Photoshop and convert the colors to CYNB. This automatically makes four color layers in (i forget the name but one of the) Photoshop window panes. Each of these can be printed (I forget if they have to be converted to greyscale first or if they can just be printed). Another option is to separate the four color phases of your print job into images and save them as a pdf).

Price for 50 prints (4 colors) on 11x7 carta bond 115g paper (fairly thick white paper) is (the equivalent of) $10usd (20 cents each).

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Natural Dyes

2019-11-15 by TTTThis

Natural dyes, for example walnut (hulls or nuts, but I read nuts produce darker dyes) or cutch (which comes from dried and powdered syrup from steeped Acacia Catechu tree wood), may or may not require scouring (preparation of the fabric by distressing/stripping it of natural waxes that protect the fabric from dying) and mordanting (fixing the color).

Generally, cotton (a cellulose based fabric) requires scouring because cotton is naturally waxy and pectin-y. When scoured, the color goes on as a darker, evener dye; when unscoured, the dye goes on in a scratchy, blotchy way. Unscoured dye jobs will not retain color as much as scoured. Cotton fabric that is already bleached may not need as much scouring.

Unscoured and scoured fabrics

To scour cotton, a container is filled with water and Synthrapol (5ml) and soda ash (aka Sodium Carbonate) (20g) is added for each half pound (250g) of cotton, and its simmered for around an hour.

Mordanting is before dying (or as a part of it) with aluminum acetate. There are other methods which use combinations of aluminum acetate and alum or use titanium oxalate. Mixed into water, 7-10g of aluminum acetate for 100g of cotton. The cotton is soaked in just water for two hours or so, then another pot of water is prepared (hot tap water) and the cotton fabric and the aluminum acetate are both added. Gloves are worn so the cotton can be worked and squeezed.

These descriptions of the process give a rough idea, but each dye has its own recipe(s) for how to achieve a good dye (there are various types of 'good dyes' with various color darknesses and tints).

For example, with cutch a deeper dye can be acheieved by first soaking the cutch powder in caustic soda (weak mixture: 1tsp for 4l of water), soaked for a hour, after which more water is added and the mix is neutralized with acetic acid or vinegar, and this is all added to the dyebath. The fabrics are then put in the dyebath and simmered for a couple hours.

Still talking about cutch, various tints can be acheived. Alum mordant causes a toffee brown dye. Iron at 2-4%wof makes chocolate browns. Soda ash rinse will redden the color. Adding 2%wof hydrogen peroxide during the final 15 minutes of dying will darken the cutch considerably. Leaving the fabric in the dyebath overnight will cause the darkest shades.

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