I’d like to ask for your wisdom in this new request I got.
I have found a local source for photocromatic and thermochromatic powders for use in different media, call it ink, acrylic, oil, etc.
What are the chances of it working when mixed with transparent white for letterpress printing?
I am asking because it is not very cheap, but it’s an inquiry from a customer to use this inks, and I’m looking at possible options to provide him with this special ink.
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enrique….. it will probably work just fine. I’m not an ink chemist by any means, but though the years I’ve made a number of special inks using powered pigments in a linseed oil base. Just this last summer I used a linseed oil- crushed charcoal ink at a Buddhist temple shop. It actually printed quite nicely.
It’s no big deal…. and it’s not the rocket science that some folks will tell you it is. That is, with Letterpress it’s not that big a deal. with offset litho, it’s a very big deal. Unless you are a chemist…. I wouldn’t shop-make litho ink.
Oil BasedTransparent White will probably work just fine, but I’ve had better luck with a linseed product called Stand Oil, used by painters. It has a better consistency for mixing and so forth, and works better with Japan drier.
I’ve never used any sort of rubber base for shop mixed ink…. so I can’t advise you on it.
Problems you may encounter:
1. drying. not all pigments are compatible with all bases, and the problems usually manifest in slow drying. Since I don’t know about your particular pigments, i can’t say. BUT most of the problems can be cured by a product called Japan Drier…. available from specialty paint suppliers. be careful though: too much Japan drier can do wierd things to your ink. Use it sparingly.
2. Viscosity issues….. your ink may be les viscous than other inks. It happens. Most of the time it will still run on your press, but you’ll have to adjust your techinque to deal with it. Normally, it’s n ot a big deal.
3. Bleed-through and/or spreading. Thin oil based inks can spread / blead on some papers. the solution is to use the minimum amount of oil with the most pigment. Of course this can get pricey if the pigment is expensive…. so you may want to use a “neutral filler” to reduce the amount of expensive pigment. for light colors this can be as simple as plain old powdered chalk or micro-silica or micro cellulose…. but you’ll have to do some experiments to figure it out for your formulas. I use powdered chalk for most colors.
4. pigment loading / coverage…. if you use too little pigment or filler, then your ink won’t cover well enough. then you’ll be tempted to put down more ink than you should…. and the result is a sloppy mess. Don’t make a sloppy mess. use a lot of pigment or filler, and make sure it will print densely enough. Of all the shop-made ink problems, THIS is the one I’ve seen most: folks try to cheap out on pigment / filler and then it won’t cover well enough. If you want to make ink, be prepared to spend the money on the pigments / fillers. like you mentioned, some of them are not cheap.
5- lumpy / gritty / clumpy pigment. your piment MUST be micro-powdered. Even the slightest grain or clumping will result in poor printing. fortunatetly, most powdered pigments are great right out of the jar.
6- toxic hazards- some pigments are NASTY. READ THE DATA SHEET BEFORE EVEN THINKING ABOUT USING A PIGMENT. Powdered charcoal is wonderful stuff. Zinc Chromate is deadly. Know what you are dealing with, and if it is even slightly toxic, don’t use it. I mean it. don’t do it. There are a lot of inert pigments out there…. so leave the nasty ones in their cans.
Finally…. is it worth it in terms of cost / effort / aggrevation? Most of the time it’s not. Store bought ink is very good nowadays, and a lot of science has gone into it’s development. for 99% of your work, you should use it.
BUT there is that 1% of work…. those special pieces that require something out of the ordinary, or absolutely lightfast, or maybe a little sparkly-er (is that a word?) than ordinary ink can provide…. and for THOSE jobs, it can be worth it.
I hope that helps. Good Luck… and let us know how it works out.
Thanks a lot for your answer, it’s definitely a very thorough answer that covers most of the doubts I had in mind.
Very encouraging too, I will definitely give this a go.
Thanks again, and I’ll be sure to get back with some answers.
To get good blending you need to use a muller and ground glass, or a litho stone. Ink makers use a rolling mill which are hard to find and not very useful unless you are making a lot of ink. You will need to add some drier, cobalt will do most of the time, it depends on the stock you are printing upon. Mixing pigment in oil the ink must be very well mixed, or you get floating pigment which can be gritty. I have seen mullers for sale on eBay, but they are also available from Graphic Chemical (at least they used to have them).
after 7 or 8 millers i usually don’t care what i have mixed. sorry Paul, i thought you said miller, my mistake.
Thanks for the info. The pigment is already ground to its finest. Where would I source a muller? Is it more or less like a mortar? I might try a molcajete :) http://guacamole-recipe.net/files/2011/01/molcajete-mortar-pestle.jpg
I might end up just making guacamole instead of ink.
@Dick, Tecate for me, but yeah.. haha
@enriquevw. Here is a link to a glass muller and glass slab, but there are others on the market so feel free to look around. It gives a good description of the process which, as it points out is to disperse the pigment rather than to grind it.