Brittle pots when adding colour?

Hi Mick, thank you for your lessons, they are really great.

I have made 100's of pots, different sizes, using both normal cement and white cement and I have had very few breakages. However I am starting to add colour pigment, black, and suddenly the pots are really brittle and breaks. I am just a bit confused as to what is going wrong, and I have checked out your mixing lesson. Do you have any ideas what is happening?

Best Charlotte

Hey Charlotte,

The added pigments seem to be the culprit. Are they formulated for concrete? Maybe the pigment is reacting with the concrete and preventing hydration from completing.

I'd try some test castings with different pigments to localize the issue. I hope that helps some.

Good luck!

jonerheim (author)  mikeasaurus6 days ago

Thanks Mike,

The pigment is formulated for concrete, synthetic, maybe the curing takes longer.

I will try different a pigment.

On a different note, I wanted to add metal into the concrete mix, what would be good to use? I am after a shine when I polish them.