The brand of high temperature plastic refractory I use is called "Plastic A", but it would seem that it must be made locally, since I have only found one source for it, and it does not seem like that is a national brand name, and not a manufacturer's name associated with it either.
It comes in a brown box with a stamped label reading "Plastic A".
The foundry supply houses are generally wholesale, and they sell bulk products, often by the ton.
It is rare to find a foundry supply house that will sell small amounts of anything, and if they do sell a small amount, it is generally 100 lbs minimum.
I have had some suppliers sell me some small quantities, and it was so much trouble for them that they no longer return my calls or emails.
I have walked into foundry supply warehouses and literally begged them to sell me small quantities of materials; most will not sell to an amateur/hobby person.
Finding quality foundry supplies is quite challenging.
A few notes on foundry safety (for those who decide to try foundry work):
For any foundry product that is purchased, you should get the MSDS (material safety data sheet) for it, and keep those sheets in a binder.
Many foundry products can be hazardous if not used and handled correctly (with the correct safety gear).
Inhaling silica sand dust, ceramic blanket fibers, cast refractory dust, parting compound dust, etc can cause you to need a lung transplant, and it is essential that commercial respirators that completely filter this material be used when you are handling and using it.
Uncoated ceramic blanket type furnaces should not be used.
Combustion type furnaces should not be used indoors, due to the fire hazards, and the hazards of low oxygen situations, and especially carbon monoxide situations. One hobby guy reported last year that he was operating his furnace in his shed, but with the door open.
Due to either low oxygen or carbon monoxide buildup (in spite of the open door) he got dizzy and stumbled outside, and passed out.
He eventually was discovered and rushed to the hospital where they were able to save him, but the doctor said that his blood oxygen level was so low when he arrived at the hospital that normally this condition is irreversible and fatal. He was very lucky.
Some folks go to the scrap yard and buy metals that are toxic. There is a type of brass/bronze that should never be melted and machined, and I forget the name of it unfortunately. Some folks try to burn the plastic off of electrical wiring, and those fumes are extremely toxic, and can do permanent damage in seconds even when inhaling just a slight wiff of them.
Zinc fumes can cause some ill effects, and should be avoided.
Alloys of brass and bronze can have zinc in them, and the zinc will burn off before you reach melt temperature.
I stick with known metals such as 356 aluminum, and gray iron scrap that breaks cleanly with a sledge hammer.
I wear nitrile gloves when handling foundry materials to avoid skin exposure.
Waste motor oil is known to contain heavy metals, and is one reason I use diesel.
The other reason I use diesel is that it is clean and uniform, with low viscosity.
Diesel will self-light using a siphon or pressure nozzle burner down to at least 35F, whereas waste oil often has to be mixed with 20-30% diesel.
Waste oil is often contaminated with toxic compounds such as antifreeze, water, or other materials, and often required straining to remove solids that will clog many burner nozzles.
I have heard that hydraulic fluid/oil is very toxic when burned.
Alternate materials/suppliers:
One way I have worked around the foundry supply difficulties is to find alternate hobbies that may use some of the same materials.
Kiln and pottery suppliers sell small quantities of high temperature materials that can be used to patch refractory in kilns or furnaces.
One material that I used a few years ago was called ITC-100, but it has gotten very expensive.
I have also used ITC-200, and I think it is less expensive and costs less.
Both of these products will dry out over time (and sometimes arrive from the suppplier dried out), in which case they can be ground back into a powder and a little water added to rejuvenate them. Never discard ITC product; it is expensive.
One company I have purchased from online (a pottery supplier) is called Clay Planet
https://shop.clay-planet.com/raw-materials.aspx
Here is a list of materials from the Clay Planet website:
https://shop.clay-planet.com/glazematerials.aspx
One product that I have not tried is bentonite, but I have seen it used as a spray-on coating for ceramic blanket for furnace interiors.
A good and inexpensive sprayer for slurry materials such as a bentonite powder/water mix is cheapest sandblaster gun that Harbor Freight makes (about $20.00 US).
I have sprayed on a slurry mix of ITC-100 on furnace interiors until the price became too excessive.
Some raw materials here including bentonite:
https://shop.clay-planet.com/raw-materials.aspx
Here is some ITC-200 for sale, and I have used it for crack repair, and it works well.
I have not purchased from this particular supplier.
https://www.ceramaterials.com/product/itc-200ez-ceramic-fill/
ITC-100 is on this page, and is much more expensive than ITC-200. I don't think ITC-100 is needed for furnace repair. It is used more as a spray on reflective coating for furnace interiors. For an iron furnace, your furnace interior will soon be coated with slag, and so don't waste your money on ITC-100 for an interior furnace coating.
https://www.ceramaterials.com/itc-coatings/
Insulating fire bricks (IFB) generally can be found in the 2,600 F rating range, and get very expensive at ratings above that.
2,600 F IFB's will not stand up to iron temperatures, and will crumble after just one firing with an oil burner, unless you use perhaps 3,000 F IFB's.
Insulating fire bricks can be hand-cut or drilled using a wood or hacksaw (avoid the dust), and so are very easy to work with.
Tractor supply and many other places sell hard fire bricks, and they stand up to iron temperatures.
Hard fire bricks cannot be easily cut, and are generally wet-cut using diamond-type tools.
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