This was the last aditive i have tried. Dodecyl benzene sulfonic acid (I'll be calling it DDBSA) is a surfactant. This means that it lowers surface tension. It can be used as a detergent, wetting agent, emulsifier, foaming agent and dispersant. I have used it as a wetting agent. As it is an acid I couldn't have added it to the liquid binder as it would slowly destroy the printhead. This way I had to get it in contact with water but not with the head. The easiest way was to coat the powder particles.

This was done by putting the powder in 0,1% DDBSA solution. Then i had let it mix for about a day (could be a lot less, but I wanted to rule out the variables). After that powder needed to be filtered. I have noticed that it is best to filter it slowly as too much flow will also wash away DDBSA molecules.

I had done many tests to find the best parameters. I won't be discussing them here as they are quite boring. I found out that mixing a 0,1% DDBSA solution and Hydroxyapatite gives good enough (we don't want to add too much additives and DDBSA is not good for human body) results at a ratio 1g of hydroxyapatite powder per 10ml od DDBSA solution. I have also found out that spray drying gives effective results at 1g/1ml ratio.

To sum up DDBSA did quite good in my case. It could be also used for some other material. But it shouldn't be used with any material, that can be corroded by acid.

P.S. This is my final log of making an overview of what I have done up to this point. I will try to continue publishing every day, but I need a topic. If you want anything specific just ask in the comments or private messages.