it's okay to have a bit of microbial or fungal growth in the jar. that's just organic material that will burn out in the kiln. remove and discard any visible fuzz sitting on top, and mix the rest of the jar thoroughly. you can disinfect it using isopropyl spray before mixing, this will evaporate quickly and not change the chemical composition of the jar contents. the final colour result should not be affected.

you can improve adhesion by adding clay to the pigment like simon does in this video, the particles in the clay body, glaze and pigment will then sort of recognise each other and stick together. it also helps if the glaze is quite fresh when you put the pigment over it.

Just add enough water so the pigment flows nicely off the brush. Not enough and it will not flow, too much and will run etc. trial and error plus experimentation.

@@sleachpots Thank you so much ❤️👍

+Peter Hayes yes it would have been better but it slakes down easily enough fairly quickly to get through screen 80 mesh

+rbanalog It is simply there as a resource to take what you wish from it. Potters have been successful at their craft for thousands upon thousands of years without the knowledge that we now have at our disposal but then they also practiced their craft without electric kilns/wheels, pre-milled materials, and most of what we simply take for granted currently. Knowing what we have learned in the last century is simply another tool to use or not at ones own choosing. I offer it as a resource if wanted, not as something your should or should not use.

+Louise B Synthetic RIO has a Higher percentage of Iron than other forms of the oxide. It is 95% Fe2O3 and 5% H2O. Spanish RIO has for example has 85% Fe2O3 and the rest is loss on ignition. It is also a finer particle size and really is ideal for glazes and decoration. However if you just want to mute your color, any RIO will work fine. Decorating, Red Saturated Glazes like the Synthetic.

+Louise B thanks disisdkat well some things technical i do not not know there. Yes when using for decoration the iron oxide is not so strong or bright as the synthetic version. You can make up a red iron oxide slip, as well as use it as i am doing in this video to use as a decorative pigment.( 75% red clay, 25% RIO for a slip, and 75% RIO, 25% red clay for a decorative pigment) Generally used on bisque ware under glaze or over glaze, and the firing range I am not 100% sure of, all I can say it works well at cone 10 !

+Simon Leach Thanks for the info, Simon. You're a great teacher!

+Louise B Also works at Cone 6! I do all the decoration when bone dry but bisque works too.

Wood ash is ash from a wood fire that is applied to the pot before a glaze fire. It give the pot a very nice texture and color thats somewhat un predictable but very nice

Clown Whisper - I'm making up a batch that is to last me a good long while ! Rather than having to keep mixing up fresh smaller batches.