critique my forge please.

[DanWilson0741]

Evening Folks, Having just finished the construction of my first forge - I would like to see if there are any views of the members about how this can/should be improved. Im not really sure if it is working perfectly, how hot it is, if my fan is strong enough etc.

All observations welcome - nothing is obvious!

kind regards,

Dan

[Latticino]

Looks great for a first forge to me.  Could improve the doors, obviously, and I hope you are running a true regulator.  Also looks like you used the wrong pipe thread tape for the gas piping.  Only thing not obvious would be liner insulating value.

[DanWilson0741]

Hi Latticino - thanks for offering your thoughts. I haven't got much experience with Propane so any pointers that seem obvious to you pls point out. I have done fairly extensive research about the build but clearly nothing beats an experienced eye run over stuff.

True regulator - Not sure what that means - its likely call it a slightly different name in the UK. Mine looks like this below.

The pipe thread tape is stuff that was recommended to me by a gas supplies company and is specific to propane use - but happy to consider a change - I need to take it apart anyway to change the gauge on it.

Liner insulation - I have approx 1 inch of castable over two inches of blanket in the base and the top. The sides of the forge body are soft bricks same as i used to make my jury rigged doors. I plan to use bricks as doors until i work out how the overall forge design works - they were an added complication during the build and I had so many different ideas about it i thought i would leave and come back to it (I will!) when the rest of the concept is proved to have worked.

Experienced views are the one bit I haven't had so far apart from reading others so very grateful for the thoughts.

Kind regards,

Dan 

[Frosty]

That's a better first forge than many made by experienced folk. 

If the tape was recommended by the gas supplier it's just a different color than we're used to. Regulator looks fine provided it's rated for propane of course.

How many times have you fired it to high yellow heat? if more than 3-4 times you probably have the right kind of IFB (Isulating Fire Brick) in the walls. A coat of a good kiln wash is a good idea regardless, it's another layer of armor between the IFB and the propane flame and people scrubbing steel against it.

1" is a lot of hard refractory for the floor let alone the roof. Lots of guys here have been doing fine with 3/8" and less. Mine has 1/2" on the entire inside. The upside to a heavy interior refractory is thermal mass, once hot it will provide fast heat to cold stock. Unfortunately the downside is it will take more fuel and time to bring to and maintain temperature. With 2" of ceramic blanket backing it the reduced insulating value isn't a significant issue.

The bricks you're using for doorways are becoming popular for being an efficient and reasonably trouble way to contain heat. Mike Porter pointed out the real benefit of closures on the doorways isn't to keep the fire in but to re-radiate infrared back into the chamber instead of radiating it to the room at large. A good quality kiln wash is a good idea for them as well.

Nice job Dan.

Frosty The Lucky.

[DanWilson0741]

Hi Frosty - yes fired it for short periods 5-10 mins each night for a week - then for half hour twice to try to bring it up to heat slowly - there was quite a bit of evaporation - the refractory had been dry for about a month - but its cold here so it hadn't been warmed at all - probably did it good to dry out slowly? I was worried about it not being hot enough originally and if I had the flame/mix/blower correct but I am happier now I think the drying out and the depth of refractory means it took time to warm up/dry out.

I struggled to find any decent kiln wash in the UK - I try to only use stuff that has been reviewed well. I will keep looking. Can I put this on now it been fired a few times?

Thank you for your input - expertise is the hardest bit to come by.

Kind regards,

Dan

[Frosty]

I'm not familiar with the hard refractory you're using but the high temp 3,000f and above, high alumina refractories do NOT dry, they set and cure by the same chemical actions as Portland cement concrete. The water forms molecular bonds with the calcite binders and is locked into the molecules. This is distinctly different from drying like fire clay or pottery clay. 

There's a very good chance the steam you observed was the ceramic blanket outer layer drying, products like Kaowool absorb and hold water like a sponge and is the typical source of propane forges steaming when lit the first time or two. 

None of that is to imply doing a heat / cool type cycle is wrong or a bad idea, it can't possibly hurt and might help. 

The IFB that used to be commonly used here only had a max sustained temperature rating of 2,200f and reacted poorly to rapid thermal cycling. I light my forge and the internal temp is into yellow in about 10 minutes. This makes the old IFBs crumble in a few cycles. There is a newer product made by Morgan Thermal Ceramics called K-26 IFB. Morgan markets and manufacturers all over the world under different names so I don't know what its called in UK if available.

Anyway, K-26 IFB have a max working rating of 2,600f are reasonably impervious to caustics like fire welding fluxes and remain hard at temperature. A coat or two of good kiln wash and it's the new consensus go to IFB for propane forges.

I don't know what kiln washes are available in the UK. The only thing I can realistically suggest is calling around ceramic supplies. Kiln washes are commonly used to protect kiln interiors from glazes or other material from sticking to the interior. 

Frosty The Lucky.