When I started diving into the various printing varieties, the salt printing immediately caught my eye. Not only do I adore the slightly romantic feel of salt printing, it’s also fairly safe and affordable to try.
This is what you need – it will seem like a long list, but you’ll find you already own most of these items:
1. An image to print. We will be contact printing the image, meaning that you will get a 1:1 copy of the negative. I have tried contact printing some of my wet plate collodion clear glass plates with some encouraging results but not everyone will have some of those lying around. We’ll be using a digital image – this specific image of the light switches has been taken in Hong Kong in 2012.
2. A digital negative from said image. I’ll explain how to make one in my next blog post. You’ll need a computer, a printer with sufficient ink and one/ several sheets of Over Head Projector (OHP) Sheets. You can buy these online or at an office supply store. I am using some I bought in Germany to try, but it seems that Pictorico is widely used and recommended. Make sure you leave your negative dry for at least 24 hours, or it can stain your print!
3. Paper to make your salt print on. You can really use whatever paper you like, but do consider ease to work with and archival values. Watercolor paper gives the images a beautiful classic look and there’s tons of brands to try, including acid-free brands. Lighter, thinner papers like Japanese tissues can give interesting effects but might be harder to smooth down after they’ve been soaked with a salt solution. Again, try looking online, a hobby/ craft or art store or a stationary supplier. I got a super cheap batch of 300 grams watercolour paper from amazon.co.uk to give this process a try.
4. Tape and boards to tape your paper to. The tape should be low-tack as not to damage your paper, like a paper painters tape. The boards should be at least somewhat sturdy, but in all fairness, I have used cut pieces of a cardboard box which seem to do the job perfectly well for 1-5 uses.
5. You will need some stuff to prepare your paper to take the image:
- distilled water (1600 ml)
- table salt a.k.a. Sodium Chlorine (10 grams)
- silver nitrate (10 grams)
- hypo a.k.a. Sodium Thiosulfate (100 grams)
- sodium bicarbonate (2 grams) or ammonia (2 ml)
6. Then there are your tools:
- trays for the (chemical) baths – these can be darkroom trays if you have them, or alternatively a couple of glass dishes or washing up tubs will do just fine – just don’t put any chemicals into a tray you’ll want to use for food in the future.
- a small pan and a heat source to warm up some of the water. Using a non-metallic stirring rod is advised.
- brushes to coat the paper, alternatively use a glass pushing rod or a piece of a washing up sponge.
- an eyedropper (optional)
- a washing line, pins and a place to hang up your paper to dry. I put mine in our tiny shower cabin.
- a piece of clear glass, larger than your intended print, or if you have one, a printing frame. Make sure the glass you are using is clean and not UV coated!
- a source of UV – the sun, a sunbed, UV lamps – all will work. I use a small Philips face tanner, picked up from a local charity shop for under a fiver.
- a source of running water.
7. Do remember to use protection kids:
- protection for your eyes (glasses)
- protection for your hands (disposable rubber gloves)
8. A space to work in:
- a room that you can black out completely, a closet or bathroom – with a red safety light. you will need this during and after sensitizing your paper. I’m using my portable darkroom I normally use for wet plating.
That’s a lot huh?
Well, here comes how to use it.
- Take a couple of sheets of paper that you want to use for your salt printing. Take your pan and heat up 500 ml of distilled water and mix in the 10 grams of salt. Stir until it is dissolved. Pour it in the tray and now dip in your sheets of paper one by one. Leave then in a few seconds and turn them over till they’re drenched. Now pin them up somewhere to dry.
- Next, warm up 100 ml of distilled water. When it is warm, put it into a (dark brown) glass container and go into your darkened room, put on your protective gear and mix in 10 grams of silver nitrate. Stir it with a glass rod until dissolved and put the mixture into an eyedropper. Be careful with this mix – it is extremely corrosive and will stain everything it touches. It could even make you go blind if it gets into your eyes! This mix is what will make your paper light sensitive.
- (optional) I use a 10 ml eyedropper bottle to coat my paper. A full bottle will coat approximately 5 full A4 sheets. I have added a few drops of a 5% mix of potassium dichromate (1-2 drops to 12 drops of silver) to increase contrast and the image does seem to turn more into a blueish grey than the normal yellow / reddish-brown. It does increase exposure times, so keep that in mind if you’re adding this step.
- Once your paper has dried completely, tape it to a support. In the darkroom, use the eyedropper to form a liquid line on one edge of the paper. Take your brush or glass rod (a glass rod is harder to control, but a brush will use more fluids) and spread the solution over the paper. You can coat it once, twice, as many times as you like – as long as you coat the paper evenly and your paper is sturdy enough to take the strain. Leave to dry in the dark. If light hits the paper, it will fog over and start to darken; your whites won’t be white and you’ll lose contrast overall.
- When this stage is completely dry, place the paper, with your negative on top (emulsion side down when using an original, protect your image by using a thin sheet of Mylar) under the sheet of glass. Place it in a spot where the sun can hit it, or use your UV light. You can check on the progress from time to time by carefully lifting the paper backing – you can see the image appear as you go along! Beware that you’ll need to make it quite dark as fixing and washing will lighten the image somewhat.
- Once you are happy, rinse the image in water for about 15 minutes to wash any unexposed silver off. Then, place the image in a fixer made from 1 liter distilled water, 100 grams Hypo and either 2 grams of soda bicarbonate or 2 ml ammonia for about a minute. Leave it a little longer if you want the print to be lighter.
- Finally, move the print to a tray with (running) water. This can be tap water, and you should leave it in there for about 30 minutes. Hang to dry, and you’re done!
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