Casting refractory stone

[Budro]

I intend to cast some refractory bricks for a wood-fired boiler. Now I would like some clarifying advice if there are any knowledgeable souls out there. I've googled a bit, and there are refractory mortar, casting mix, plaster, etc. I assume that refractory plaster becomes quite fragile. Or? But can you cast a type of brick with mortar? Casting mix does not seem to be available "everywhere" (i.e., regular hardware stores) whereas refractory mortar is. Some casting mix must be mixed with a forced mixer according to sellers. A regular concrete mixer is not sufficient. Neither is hand mixing. But mortar can surely be mixed/whisked by hand, right? The idea is to use a mold. I would appreciate some input from those who know more.

 

[jonaserik]

Is it because you're lining a wood-burning stove on the inside, they have then crumbled in the heat, entirely normal. Trying to do something yourself will be difficult, as the original ones are sintered (molded under high pressure and vibrated) leaving almost no moisture in them. If you try it yourself, moisture will remain for months, even though you think they are dry. When you then put them in the stove and start the fire, the moisture will expand (explode) and crack. I've tried inserting better quality firebricks, but they cracked as well.

 

[fribygg]

I recommend trying vermeculit boards if they are simple shapes.
@Kalle B has tried casting and maybe can share some experiences?

 

[Budro]

There are base stones in the pan. I have replaced them several times before. The last ones I bought are definitely cast. Hence the idea to try it myself.

 

[Kalle B]

I recommend trying vermiculite boards if the shapes are simple.
@Kalle B has tried casting and might be able to share some experiences?

I have cast side stones for my stove, but it doesn't get as hot there as in a modern boiler. Anyway, I cast using regular concrete that I bought at Byggmax, nothing particularly heat-resistant. I've been burning all winter, and the stones still look like new. Absolutely no weathering or flaking, but of course, I burned carefully the first time to dry out any remaining water.

 

[Tia78]

I have used Höganäs refractory castable to cast new stones for a pre-furnace with excellent results. Depending on the size, you can after-dry in the oven where you gradually increase the heat.

 

[Tia78]

I have used Höganäs refractory casting compound to cast new stones for a pre-furnace with excellent results. Depending on the size, you can dry them in the oven by gradually increasing the heat

 

[Budro]

[image] [image]

I used Höganäs refractory casting compound to cast new stones for a pre-furnace with excellent results. Depending on the size, you can dry them in an oven where you gradually increase the heat

Did you buy it online or is it available in some hardware store? Did you use a forced mixer?

 

[Tia78]

I bought it from gärdin and persson in Östersund but there are more companies that sell it and I mixed it together in a bucket with a wooden stick. I have been firing in the fore furnace for a few years with newly cast parts so it seems to work well.