Refrax setting very quickly!

[stchang]

I just laid my Forno Bravo oven floor today, and I had a huge problem with the Refrax harden as soon as I spread it on the insulating layer. I actually wasted a bag, because I thought I mixed it too dry and started over.

On the second attempt, it still set almost as fast even though I mixed it very wet (about 3L for the bag). Should it have been wetter?

I did wet the hearth and the floor pieces before applying the refrax. I suppose it is too late to ask for tips, but others may be able to benefit from them.

Otherwise it is going great. Hope to have the dome up this week.

[Johnny the oven man]

OK, listen up, Im only gonna tell you once. To retard the setting of refractory castable, use a spoonfull of SUGAR. Dont laugh. To accelarate the setting use either Lithium Carbonate or Sodium Aluminate. All these DO work. 30 years in the refractory game and Ive learnt something. lol

[james]

Hey stchang,

Did you get the floor and the under oven insulation wet? The Refmix should also be well-hydrated.

Of course what matters is how it came out. Did it set OK in the end?

Let us know, and let us also know if you are running short of Refmix. We can get you another bag if necessary.

James

[mfiore]

Is it necessary to mortar the floor down? Many of us building the Pompeii are just using some dry fireclay/sand mix to level the floor. The oven is very heavy. I don't think it will move. I can't speak for the pre-fabricated floor, but I can't see how that is different.

[stchang]

Thanks for the responses.

I think I still have enough Refrax to complete the oven. Thanks for the offer, though.

Also, I've seen the other plans where the floor was not mortared down, so after an initial panic, I just concentrated on using the refrax to get the floor level.

[dmun]

The FB board, Cal-sil, absorbs all water on contact. Any leveling material, whether refractory mortar or fireclay-sand, should be used dry. That said, you shouldn't need to use anything on top of the insulating board, as it leaves a flat surface to work on.

[egalecki]

Originally Posted by Johnny the oven man

OK, listen up, Im only gonna tell you once. To retard the setting of refractory castable, use a spoonfull of SUGAR. Dont laugh.

after watching my plasterer put Sprite and Mountain Dew into plaster to keep it workable longer when doing a ceiling, I will never laugh at something like this.....

[jengineer]

Humm Mountain Dew - doe the plater have a slight green tinge to it?

[james]

You can put the FB Casa and Premio floor on a leveling material (such as a sand and fireclay mix) and I know folks who have done it, but the manufacturer recommendations mortaring it in place. One thing to note is that the pie shaped floor piece angle inward a little, so the joint is a little wider than a firebrick floor, and you can pack Refmix into that joint to fill it in. Of course you have fewer joints. I don't think it is a very big difference either way.
James

[egalecki]

Originally Posted by jengineer

Humm Mountain Dew - doe the plater have a slight green tinge to it?

no, but it required painting because it wasn't evenly colored... I'm not sure, but I think half was sprite and half was mountain dew...

It smelled very odd as it cured, I might add..