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UK Firebricks that are not too thick? (for floor of gas forge)


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Looking for firebricks for the floor of a gas forge. The forge doesn't have much height, and as I'm putting in blanket and refractory cement, so there'll be even less height.

So, firebricks shouldn't be too thick, maybe like 20mm? 

Any recommended ones that don't crumble after 3 or 4 heats?!

OR, if I have used blanket & refractory, do I need firebricks on the floor? - I've not used refractory cement before so need advise! (more used to coke forges, just getting in to gas forges).

Looking at the blanket & refractory cement below... Will be doing mixed forging, variety of things but to include forge welding at times.

https://shop.vitcas.com/vitset-45-refractory-mortar-ready-mixed.html
https://shop.vitcas.com/ceramic-fibre-blanket-ceramic-insulation-mtr.html

Thoughts on firebricks, if they are needed, and/or if the above 2 products are decent? (Do I need a rigidizer too or can I get away with the refractory straight onto the blanket?).

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Bricks are rarely a good idea, they always crumble.  Some people just use them as a consumable, and that's fine.  Your ceramic fibre choice will work fine.  The 1430C is of course better, but since you're putting a lining in the lower temp stuff will be fine.  Use two layers for optimum insulation.  

 

As for the mortar, hopefully some of the other Brits on here (Paging @timgunn)! will give you a better answer, but the mortar is not going to last.  It is designed for thin joints in firebrick kilns or fireplaces, and will crack in short order in this application.  A quick look at that website shows me this stuff which will be infinitely better:

 

https://shop.vitcas.com/refractory-castable-grade-1700.html

 

More expensive, but cast a floor about 15-20mm thick, run it up the walls a bit to form a basin and you're fluxproof and good for a very long time indeed.  The two reviews are from guys who have made forges from it.  This stuff looks good too:

 

https://shop.vitcas.com/vitplast-45ab-mouldable-refractory.html and has the advantage of just ramming it in place and firing up.  make a floor, again 15-20mm thick, with little walls to prevent flux leakage.  

 

I was looking for an insulating castable or rammable like kast-o-lite 30, but I'm not seeing it at Vitcas.  

 

Never bother with rigidizer.  It lowers the insulating value of the wool, and is meant mainly to prevent sagging in boiler or home furnace fireboxes.  You do need something to seal the fiber in the walls and roof above the floor, and the mortar may serve there.  However, any of the following would be better:

 

https://shop.vitcas.com/products/heat-resistant-materials/refractory-coatings.html

 

These are meant for that job.  I'd get the powder and mix it to a thick paste to trowel on the walls and ceiling a bit at a time.  5mm or so will do the trick.  It will crack, but it can be patched easily enough.  

 

 

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On 9/19/2021 at 9:01 PM, Alan Longmire said:

Bricks are rarely a good idea, they always crumble.  Some people just use them as a consumable, and that's fine.  Your ceramic fibre choice will work fine.  The 1430C is of course better, but since you're putting a lining in the lower temp stuff will be fine.  Use two layers for optimum insulation.  

 

As for the mortar, hopefully some of the other Brits on here (Paging @timgunn)! will give you a better answer, but the mortar is not going to last.  It is designed for thin joints in firebrick kilns or fireplaces, and will crack in short order in this application.  A quick look at that website shows me this stuff which will be infinitely better:

 

https://shop.vitcas.com/refractory-castable-grade-1700.html

 

More expensive, but cast a floor about 15-20mm thick, run it up the walls a bit to form a basin and you're fluxproof and good for a very long time indeed.  The two reviews are from guys who have made forges from it.  This stuff looks good too:

 

https://shop.vitcas.com/vitplast-45ab-mouldable-refractory.html and has the advantage of just ramming it in place and firing up.  make a floor, again 15-200mm thick, with little walls to prevent flux leakage.  

 

I was looking for an insulating castable or rammable like kast-o-lite 30, but I'm not seeing it at Vitcas.  

 

Never bother with rigidizer.  It lowers the insulating value of the wool, and is meant mainly to prevent sagging in boiler or home furnace fireboxes.  You do need something to seal the fiber in the walls and roof above the floor, and the mortar may serve there.  However, any of the following would be better:

 

https://shop.vitcas.com/products/heat-resistant-materials/refractory-coatings.html

 

These are meant for that job.  I'd get the powder and mix it to a thick paste to trowel on the walls and ceiling a bit at a time.  5mm or so will do the trick.  It will crack, but it can be patched easily enough.  

 

 


Excellent, thanks!

REALLY appreciate the details response and links/explantions - A HUGE help, cheers :D

Edited by Mike Gracia
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When I last did my forges I bought 1600c rated refractory cement from ebay, and cast the floor, and walls with that. It was 1/2 the price a few years ago though! - https://www.ebay.co.uk/itm/264332519138?hash=item3d8b7226e2:g:KhkAAOSwqF5bl-Da

 

It mixes up like lumpy concrete, but is bomb proof once you have gone to the effort!

 

edit to add, I use a couple of inches of insulating wool, with the refractory cast inside that. The refractory cement takes much longer to heat up than wool, but holds the heat when you put the workpiece in, and is flux resistant!

 

Edited by John N
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2 hours ago, John N said:

When I last did my forges I bought 1600c rated refractory cement from ebay, and cast the floor, and walls with that. It was 1/2 the price a few years ago though! - https://www.ebay.co.uk/itm/264332519138?hash=item3d8b7226e2:g:KhkAAOSwqF5bl-Da

 

It mixes up like lumpy concrete, but is bomb proof once you have gone to the effort!

 

edit to add, I use a couple of inches of insulating wool, with the refractory cast inside that. The refractory cement takes much longer to heat up than wool, but holds the heat when you put the workpiece in, and is flux resistant!

 

Thanks! Hmm so wool first, then coat with refractory (similar to others mentioned above?

On 9/19/2021 at 9:01 PM, Alan Longmire said:

Bricks are rarely a good idea, they always crumble.  Some people just use them as a consumable, and that's fine.  Your ceramic fibre choice will work fine.  The 1430C is of course better, but since you're putting a lining in the lower temp stuff will be fine.  Use two layers for optimum insulation.  

 

As for the mortar, hopefully some of the other Brits on here (Paging @timgunn)! will give you a better answer, but the mortar is not going to last.  It is designed for thin joints in firebrick kilns or fireplaces, and will crack in short order in this application.  A quick look at that website shows me this stuff which will be infinitely better:

 

https://shop.vitcas.com/refractory-castable-grade-1700.html

 

More expensive, but cast a floor about 15-20mm thick, run it up the walls a bit to form a basin and you're fluxproof and good for a very long time indeed.  The two reviews are from guys who have made forges from it.  This stuff looks good too:

 

https://shop.vitcas.com/vitplast-45ab-mouldable-refractory.html and has the advantage of just ramming it in place and firing up.  make a floor, again 15-20mm thick, with little walls to prevent flux leakage.  

 

I was looking for an insulating castable or rammable like kast-o-lite 30, but I'm not seeing it at Vitcas.  

 

Never bother with rigidizer.  It lowers the insulating value of the wool, and is meant mainly to prevent sagging in boiler or home furnace fireboxes.  You do need something to seal the fiber in the walls and roof above the floor, and the mortar may serve there.  However, any of the following would be better:

 

https://shop.vitcas.com/products/heat-resistant-materials/refractory-coatings.html

 

These are meant for that job.  I'd get the powder and mix it to a thick paste to trowel on the walls and ceiling a bit at a time.  5mm or so will do the trick.  It will crack, but it can be patched easily enough.  

 

 


Hey Alan, thanks again for your detailed reply. I just want to make sure I get it right :D So would it be...

1 - Ceramic fibre/wool

2 - Then something like this to coat the wool https://shop.vitcas.com/products/heat-resistant-materials/refractory-coatings.html
3 - THEN this as the final coat 

https://shop.vitcas.com/refractory-castable-grade-1700.html

Did I get that the right way around?

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Close!  Wool, castable, and then if you think you need it, the zircon stuff.  

 

I'm glad John chimed in, he's in the greater Manchester area and knows his industrial stuff.

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