Hi, I'm starting to build my first oven (North West Ireland). I've gotten some powdered clay from a pottery friend of mine, I think its slip clay?

I've mixed my first batch two nights ago. and used it to cover the layer over my wind bottles and as a base for my fire bricks. I used a mix of 2:1 sand to powder, the consistency seemed good, don't fall apart or splat when ball dropped from waist height.

It's drying slowly since, still soft to touch, weather cool. But I've noticed a few cracks appearing as it starts to harden. Not major issue for this layer but worried about actual oven dome if happens again.

Is this normal or what changes should I make to mix?

I've seen elsewhere that I should be using Homebrew instead - Sand/Cement/Lime/Clay in the ration 3-1-1-1 by volume? And dry curing for a few weeks - seems a long time?

Thanks in advance for any help

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