Sign in to follow this  
Zachary

Greencast 94 refractory questions

Recommended Posts

I have recently got into making pattern welded steel and it's being hard on my kast o lite 30 forge floor. I've heard of and found a place to get some greencast 94 and was thinking about using it for my floor as it's supposed to hold up to flux better. My question is with heat retention. It says it has good heat retention but I read somewhere on here that it's more of a heat sink than other castables and makes it hard to get your forge up to temperature and I don't have any heat to waste. I have 2" of kaowool underneath it is it gonna be a problem as a heat sink and will it hold up to flux enough better than kast o lite 30 to be worth it? Thanks Zachary

Share this post


Link to post
Share on other sites

You seem to think you have an either/or problem. What keeps you from using a thin coat of it over the Kast-O-lite?

Share this post


Link to post
Share on other sites

I didn't even think of that thanks! Do I need to do anything special to get them to bond? Can I just cast a layer over my current floor to repair it or should I pour a new one and coat the top when it's damp? Thanks again. Zachary

 

Share this post


Link to post
Share on other sites

No problem, they'll bond fine. Make sure the existing floor is clean and free of loose debris and wet it before applying the Greencast. They are very similar products the main difference is in % of alumina refractory to calcium binder (cement) and aggregate. The Kastolite contains evacuated silica beads as part of the aggregate and this makes it a little more susceptible to hot borax based flux.

In future when a refractory maker or furnace guy talks about "heat retention" here we talk about "heat sink" this is heat the refractory collects and holds onto. If you're running a high volume quick turn over furnace then a high heat retention furnace wall is a good thing. It may take more fuel to bring it up to temperature but it will stay hot longer when you open the doors to exchange hot for cold stock and close them up again, this makes the stock heat faster. Good for high production. This type furnace is usually left running 24/7 because of the fuel costs to heat it back up and the damage done by thermal cycling.

However what we do in a small smithing shop is slower paced, maybe a few hours a day two days a week. Maybe. For us we want a forge that heats up quickly and doesn't suffer for heating up and cooling off quickly. For what we do as little thermal mass as we can get away with is the better deal. However insulating refractories like Kaowool are fragile especially at forging temperatures not to mention shedding sharp ceramic fibers that are a breathing hazard. So, they need some armor, first stiffen it up in general with a rigidizer then apply a layer of something concrete hard and relatively immune to hot caustics like welding fluxes. 

I have some greencast 94 and the stuff is bulletproof for the worst I could do to it. I switched to Kastolite 30 for a couple reasons: It's less expensive, here anyway, more significantly it's a reasonably good isulator and most significantly it's concrete hard above easy welding temps and laughs at the welding flux I use. "Petersons blue." The Peterson's is off the shelf at the local welding supply for about $1/3 one of the "Forge Welding Fluxes" sold by blacksmith suppliers. The stuff's anhydrous borax, boric acid and something to turn it blue. Peterson's makes a flux that also includes iron oxide like some of the "real" forge welding fluxes but I can't understand why we brush so HARD to remove scale (iron oxide) just to include it in the flux. There's lots I don't know so take that as my opinion for what it's worth.

Anyway, I tested Kastolite 30 by putting a heaping Tbsp. on yellow hot Kastolite. Nothin, nada.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Thanks for all the info. I should find that flux the stuff I’m using is eating my floor but I can’t remember the name of it at the moment. Thanks again guys.

Share this post


Link to post
Share on other sites

I'd be interested to know what brand flux damages Kastolite 30. It's more important to know about things that don't work in many cases.

I picked up the can of Peterson's after reading the ingredients and assumed it'd be about as caustic as any of the similarly formulated "forge" welding fluxes. Well, okay the price $26 and change for a 1 lb. can had something to do with it I'm sure. 

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Straight 20muleteam borax will do the trick frosty.  Turns the kastolite in to a sticky glue like substance.

Share this post


Link to post
Share on other sites

Binesman that's exactly what the flux I'm using does I think it's called ez weld anti borax I got from blacksmiths depot. Have you found something you like that doesn't eat the floor?

Share this post


Link to post
Share on other sites
22 hours ago, Frosty said:

o problem, they'll bond fine.

Ya did it again, Frosty; off this goes to Forges 101 :D

Share this post


Link to post
Share on other sites

Hey guys I'm getting ready to try a ribbon burner and I have some Kast o lite 30 and some Greencast 94. I read that Kast o lite 30 isn't ideal for a burner but I can't find anything about the greencast. Would it be suitable or should I get something else? Thanks Zachary

Share this post


Link to post
Share on other sites

I’m getting ready to try and make a ribbon burner. I have some Kast O Lite but have read maybe that isn’t the best for this. I also have some greencast would that work for a burner? Thanks Zachary 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this