Preconditioners & Cover Material

Preconditioners are typically used in grey iron when aluminum levels are too low. Preconditioners are added to increase the aluminum levels to increase the nucleation sites to form type A graphite. If the nucleation levels are too low, you will have a poor graphite matrix. Preconditioners are added when the heat is ready to pour, and the extra aluminum will increase the nucleation sites, resulting in better graphite.

Cover material is used for ductile iron. This is placed over the magnesium alloy to delay the reaction time. One to one and a half percent cover material is typically used based on the weight of the metal. However, you can add too much cover material, which will delay the reaction until the ladle is almost full. This can cause poor treatment and spitting or bubbling the metal out of the ladle. You want your reaction to start when the ladle is half to two-thirds full. If the mag alloy reacts as soon as you pour metal in, you do not have enough cover material, or your alloy pocket is improperly placed or sized.

Carpenter Brothers can assist you in determining what preconditioner you should be using and how much cover material to use. We can also with the design and placement of your alloy pocket.


Preconditioners & Cover Material Products

Carpenter Brothers, Inc. offers a complete line of foundry products to meet the requirements of the Metalcasting Industry.

Foundry Products

We supply the necessary foundry products you need to make a quality casting. Whether you need Metals & Alloys, Melting & Melt Quality, Molding & Core Making, Casting & Shakeout, Finishing & Surface Preparation, or Environmental Compliance products, we have what you need.

Metals & Alloys

Alloys for Aluminum, Brass, Bronze, Gray & Ductile Iron, and Steel castings. 

Melting & Melt Quality

Everything you need to produce molten metal.

Molding & Core Making

Additives, risers, chaplets, chills, bentonite, resin systems, and coatings you need to make a quality casting. 

Casting & Shakeout

Products to aid you in casting and shakeout.

Finishing & Surface Preparation

Abrasives, carbide burrs, grinding and cutting wheels you need to process castings


PPE, dust control, baghouse, and waste management products to keep you in compliance. 

About Us

Carpenter Brothers, Inc. is the leading supplier of equipment, consumables, and technical expertise for the metal casting industry. Founded in 1917, by Everett and Milton Carpenter, the brothers were able to use their unique foundry experiences to solve the problem of the day: a reliable sand source.  They got their foot in the door by selling natural bonded molding sand, which was mined by hand, loaded into horse-drawn carts, and then delivered to customers.  Not only did they sell the sand, but their technical expertise was readily available for all customers, big or small, to help manufacture the best castings. After surviving The Great Depression, Carpenter Brothers, Inc. slowly increased the number of products it distributed and expanded its sales territory into what it is today.


Carpenter Brothers, Inc. has committed itself to its customer's success by providing exceptional service to go along with the superior products and equipment they supply.  With multiple warehouses around the United States we can get you the products you need when you need them. Our logistics team can handle getting your order to you by truck, plane, or train. Our technical sales and engineering staff all have experience in the industry, so when you buy from Carpenter Brothers you gain access to all of our knowledge.

Contact Us for a Quote

We are here to assist, give us a call or send us an email with your questions or quote request and we will be happy to help.