I just mixed up my first batch of ink this weekend, and after doing so I was looking through the ink recipe forum and saw a lot of talk about precipitation. I know what precipitation in general is, but in terms of ink mixing is it just the forming of condensation inside the bottle of the mixture? What are the negative things that can happen to a pen with this ink put into it? What is it that makes it an undesirable characteristic?

By the way, with my mixture I was trying to get a nice deep purple, and mixed 16 cc PR Black Magic Blue, 10 eye droppers of Noodler's Nikita and 6 cc of Waterman Black. I'm very happy with the results, but a little nervous about causing lasting damage by not knowing what I'm doing.

I think they were meaning solids that precipitated out, and those solids could clog feeds.

exactly, when mixing two solutions a chemical reaction can occur, producing a solid substance. simple chemistry

that is why it is recommended that you test using only minimal amounts of ink before creating a whole batch

Hi JS,

Precipitate is indeed solids coming out of the resulting solution. These can clog up the channels in the feed and, depending upon what they are made of, be very hard to remove. The safe thing is to let your mix sit overnight and check it in the morning and see if anything has settled out to the top or bottom, assuming you mixed in a transparent container. If not, pour it into one and then let it sit overnight.

Keep us posted,
Michael

Precipitation is the formation of insoluble reaction products, resulting from mixing different types of inks. Fountain pen inks are largely water, however they also contain small amounts of dyes and various agents to help flow, keep the dye in solution, adjust the pH, prevent microbial growth and scads of other things. Generally speaking, all the ink from a particular line is very similar and can be mixed freely. Ink from different manufacturers can vary greatly chemically depending on their particular proprietary recipe. So, if you mix Company A's blue with Company B's black, there is a chance that some chemistry will occur and a solid product can result.

These precipitates can cause a variety of problems:
a.) as mentioned by the other posters above, they can clog narrow feeds
b.) if they are slightly soluble, they can cause extreme local pH's or electrochemical corrosion effects.
c.) they can cause a loss or change to the ink colour as they react

The advice posted previously is sound. If you must mix inks of disparate types, you are best off doing it in a separate container and watching for a day or so to see if any odd things happen.