Hi Everyone,

 

I am building my second forge, my first being made with ceramic wool, This new one is a castable forge using kast-o-lite 30. I poured the castable in the forge about 2 weeks ago and it has been drying since, I have been making some of the hardware to finish the forge and also building the burner in that time. So I have the burner built I just need to get the castable fired for the first time. I have no way of controlling temperatures for extended periods just able to fire my burner on and off to sustain a temp. Any ideas for heatup on fresh castable?

 

Thanks in advance.

Hi. You can build a fire with pine sticks then dump in a bag of charcoal briquetts. By the time it cools down it will be dried out enough. 

WayneCoe sells castable and builds furnaces, and is a good source to ask about making one.

Last castable I made put a heat lamp in one endand blocked off half of the other end so moisture could escape. Left it on 24/7 for 4 or 5 days.
First fire only for about 10 min. Next few fires each a little longer then go for it.

Last castable I made put a heat lamp in one endand blocked off half of the other end so moisture could escape. Left it on 24/7 for 4 or 5 days.
First fire only for about 10 min. Next few fires each a little longer then go for it.

This sounds more reasonable, as I said it has been sitting drying for 2 weeks I have left it to get as hot as it can in the sun so any moisture on the surface has been driven out. I just need to bring it to operating temp slowly without any explosions. I do expect it to crack as it is a continuos cylinder and there is one thinner spot at the top but I don't want it to spall.

I will take a picture a little later.

Here are some pics of the forger.

First the burner, I am pretty excited about this guy.


The forge, it is missing some hardware namely the legs which I hope to get welded on later today.

That unit is small enough you can probably bake it in the oven for a few hours on low.

If it puts your mind at rest…the first time I came across castable was when I was given a few bags by the foreman at a drop forge works that I bought a Massey hammer from.

 

When I used it to make a furnace base, I looked up the handling spec. which referred to incrementally raising the temperature 15 degrees every hour for days.

 

I phoned the foreman and asked how to control the temperature increase. The answer was "Ignore it! when we are going to recast a furnace we turn it off after the shift on Friday night, smash it apart, recast it, light a small flame on Saturday morning, leave it burning over the weekend, Sunday night it is turned up flat out and is ready to use by the Monday shift…sure they crack, but they still work fine with the odd crack"

 

My first castable furnace lasted for 15 years and we only replaced it because we were idle while waiting for a project to get under way. It had tonnes of steel through it in that time. It was cracked and worn around the mouth but I did not notice any increase of efficiency when we recast it.

 

Alan

If it puts your mind at rest…the first time I came across castable was when I was given a few bags by the foreman at a drop forge works that I bought a Massey hammer from.

 

When I used it to make a furnace base, I looked up the handling spec. which referred to incrementally raising the temperature 15 degrees every hour for days.

 

I phoned the foreman and asked how to control the temperature increase. The answer was "Ignore it! when we are going to recast a furnace we turn it off after the shift on Friday night, smash it apart, recast it, light a small flame on Saturday morning, leave it burning over the weekend, Sunday night it is turned up flat out and is ready to use by the Monday shift…sure they crack, but they still work fine with the odd crack"

 

My first castable furnace lasted for 15 years and we only replaced it because we were idle while waiting for a project to get under way. It had tonnes of steel through it in that time. It was cracked and worn around the mouth but I did not notice any increase of efficiency when we recast it.

 

Alan

 

 

 

 

thanks that really does put my mind at ease. Once I get the feet on it I will fire her up!

His tale certainly stopped me from worrying about it. :)

 

What I have done is light a soft flame leave it on for a few minutes, turn it off leave it off for a few minutes, light a soft flame, leave it on for a few minutes and etc…I tend to do that with my big furnace (which I keep outside under a tin sheet) if that has been idle for a while. Especially in winter when it is damp, I go throughout the same gentle start up. In fact I think most of the damage I have done to the furnaces has been relighting after a prolonged period of non-use, more than the impatience/lack of finesse in the original firing. In the winter I use the steam being driven off as a guide, as soon as it steams turn off the heat when the steam diminishes warm it back up...

 

Have fun with it, Alan

Did you read the directions on the bag? I believe Castolite has the cure data on the bag. A couple factors can effect dry and cure times typically ambient temperature and humidity are about it. If it's reasonably dry a light bulb for a couple days is more than enough, even in 90% humidity a day or two with a light bulb usually does the trick.

 

I'm a conservative kind of guy and usually will light a burner for a few minutes shut it off and look for steam. If it's steaming ANY I let it steam for a couple hours and fire it again for maybe 15 minutes, shut it down and look for steam. I've never seen steam on the second dry firing. Then I'll light it off and when it starts coming to red I shut it off, block the ends and let it cool. After that I put it to work.

 

The guys at EJ Bartells looked at me like I was a voodoo priest discussing mystic stuff and told me to just let it dry a couple days, light bulb is good and put it to work. That's the GreenCast 64 I'm using in my new forge.

 

The refractory I used in my first forge is no longer available but it was just plain bullet proof on our level of HOT. Gross overkill maybe but it's still perfectly fine after more than 25 years

 

Frosty The Lucky.

So I finally got her time and guts to heat this thing up. I am very happy with how things turned out.

So I fired the burner for 10minutes than shut it off till the steam stopped than repeated but shorter firings the next few times as it didn't take much for it to get steaming again. When I finally let it go for a while what I thought was steam was actually the paint and adhesive starting to gas out.

Some pics for fun.

This is at 10psi


This is at 15psi

A couple more pics. I added some doors to

Did it crack yet? :)

 

Alan

Alan it did not crack. There was some light spalling at the mouth where the castable is at its thinnest. Interestingly the top of my burner was sweating a few times during initial heat up. So far I have only gone to 20psi which gets it plenty hot and I know extended use at that pressure will freeze over my 20# tank.. I need a 40# tank atleast.