Dome render multiple hairline cracks

[Lambooni]

Hello,

I have been curing my oven. 1st day at 300F, second at 350F. Many small hairline cracks have appeared in my render.

It even actually cracked before any curing fires, just at it was naturally drying for a week and a half!

I did accidentally used the wrong mix of sand:lime:cement. I used a 2:1:1 rather than what I was supposed to of 4:1:1. Could this be my issue and if so will it effect the cooking ability of my oven - I expect/hope not!

My plan is to continue curing for about 5 - 10 fires, then fill any of the bigger cracks with fire cement, then use a flexible masonry paint to cover everything, hopefully hiding the hairlines.

Does this sound like it could work?

Thanks,
Adam

[david s]

Re: Dome render multiple hairline cracks

I've found it much better to drive out the water before doing the outer rendered shell to prevent the problem you describe. The outer shell is only to keep out the weather so a second layer of elastic acrylic render should do the trick, but give the thing about 10 decent firings first to make sure all the steam is out.

[boerwarrior]

Re: Dome render multiple hairline cracks

I agree with David - in hindsight it would have been better to cure the dome before adding insulation and render (lots of discussion about this elsewhere in these forums).

However, no harm done. It will just take a little more time to dry out. Hairline cracks are normal. I filled in a few of mine and then I just let them be. They don;t affect my oven performance at all. Oh and what David said - don't apply the acrylic until you are thoroughly dry!