To Clad or To Not Clad

[Gentcpa]

Hi:

I have seen various discussions on here regarding cladding and I am trying to decide what to do.

The benefits seem to be more resistance to cracking and extra thermal mass. The negatives seem to be extra thermal mass (longer heat up times) and maybe a wasted step with regards to time and materials for something that isn't required.

So just looking for some discussion on this. Right now the exterior of my oven is nice and clean with no excess mortar and is almost complete.

Thanks


Julian

[rlf5]

If you don't get any cracks from your first few fires, then I say don't clad. If you do get cracks, then I say patch the cracks and don't clad. With adequate insulation, your oven should have more than enough thermal mass to roast and bake with.

[oventhusiast]

I just put a layer of heat stop 50 over my oven. It had some cracks (see pics) and I patched them with furnace cement. It seemed to be ok but I wanted to give the whole dome a bit more integrity. I used a 50 pound bag which really gave me about one half inch or less of a cladding. It's as hard as a rock but only a full fire will tell if it cracks like a hard boiled eggshell! I really don't know if I needed this but I think it will (or may) stop some movement. I hope I didn't waste my time (or money) but I'd like to think it's a bit of insurance against further cracking after the dome gets a watertight 'house' built around it.
Rick

[Frances]

As I've said before, I'm not cladding because of the mortar I'm using, which has no cement component and would no way work for cladding. And adding cement cladding now that I've gone with the non-cement version seems a bit of a contradiction.

However, if I had used cement-based mortar I think I would clad just to be on the safe side. Unless I had run out of mortar, in which case knowing me, I'd do without.

Not much help really. I do hope someone with some real building knowledge chimes in on this one...

Maybe it just doesn't really matter all that much?

[wlively]

I added a thin layer of cladding mainly as an extra shell of containment.

Unless you are adding an inch or more, I don't think you are making a significant or noticable amount of thermal mass to the oven.

[sarah h]

I've only got a tiny bit of mortar left, which may or may not be enough to patch any crack that appear once I fire it up. If it is enough, that's it - no cladding. If not, I'll get a 10 lb. pail, do my patching, then throw what remains on top simply to use it up. I'm hoping it won't come to that though ...

Sarah

[gjbingham]

I'm not sure if you would call what I did cladding. I used the fireclay/sand/cement and lime mix for mortar vice Refmix. I don't think this mix is truely refractory like Refmix.

I added about a half an inch all the way around, just to button things up along the external mortar joints, where frequently, the mortar would pull away from the bricks as it dried, leaving minute gaps. This half-inch layer has developed it's own cracks as it dried in the afternoon sun.

Barring major structural cracks, I'm not sure that I will worry too much in the early firings if I see smoke/steam from the dome.
George