Q. What makes MR-97 Boron Nitride Mold Release Aerosol different from other Boron Nitride sprays?
A. The formula for MR-97 was developed for industrial customers. With 15% to 20% Boron Nitride by weight in the can, it has significantly more than the 1% to 5% in the other brands. Boron Nitride keeps your glass from sticking to the mold. Even with several coats of the other sprays, you won’t get as much Boron Nitride on the mold as with one coat of MR-97.
Q. What’s the maximum temperature I can use with MR-97?
A. MR-97 has been proven effective with glass at temperatures up to 1800 F. Unlike other Boron Nitride aerosols, MR-97 uses a proprietary double binder system. One binder works from cold to about 1300F then the second binder takes over up to 1800F.
Q. What’s a binder?
A. The binder makes the coating stick to the mold.
Q. Why is it important to shake the can every time I use it?
A. The aerosol can contains liquid Boron Nitride coating and propellants, which are gasses. When the aerosol sits, even for a few minutes, the liquid settles to the bottom of the can. Shaking the can for a minute or so re-suspends the liquid so it can be propelled from the can.
Q. Why must the can be held upright when spraying?
A. By “upright” we don’t mean “perpendicular.” There is leeway for normal tilting of the can. When the can is held at a sharp angle, the internal feed tube, which is attached to the spray head and extends to the bottom of the can, will come free from the Boron Nitride liquid and pump mostly propellant. This is particularly true when the can is almost empty. Hold the mold in a gloved hand or prop it up so the cavity you’re spraying faces the upright spray can. NEVER put your mold flat on a table or on the floor and spray down into it.
Q. Can I use MR-97 with all of my molds?
A. MR-97 can be used with both ceramic and stainless steel molds of all sizes. For shallow molds, simply spray the coating onto the mold and let it dry before casting. For deep molds, we recommend that you burnish the coating before casting to keep the MR-97 from being dragged into the glass as it melts.
Q. How do I burnish the MR-97?
A. After the coating is dry, lightly rub the surface with a soft cloth, like an old T-shirt. This smooths the surface of the coating so the melting glass will slide down easily.
Q. Is MR-97 safe?
A. MR-97 is a solvent-based coating. When correctly used, it is very safe. Use in a well-ventilated area, keep it away from extreme heat and open flame, and use a dust mask while spraying. See the Material Safety Data Sheet (MSDS) for full details.
Q. How should I clean overspray on my hands or work surfaces?
A. MR-97 is easily washed off with soap and water.
Q. Is it necessary to sandblast a stainless steel mold prior to the first application of MR-97?
A. Sandblasting is not recommended. While the MR-97 will adhere better to the sandblasted surface, it will roughen the mold – and that will affect the surface of the glass. The best way to prepare a stainless mold is to wipe it with alcohol or acetone to remove all grease and oil from the surface. The MR-97 will adhere well enough to the cleaned surface to give you the release you need.
Q. Why do I have to brush the mold after firing? If there’s MR-97 left on the mold, can’t I just reuse the mold without spraying again?
A. MR-97 leaves a flaky residue after firing that is removed by brushing out the mold. It’s important to get the loose flakes out so they can’t become trapped in the glass during your next firing. The brush needs to be firm enough to remove the loose particles but not so stiff it scratches your mold. MR-97 penetrates the surface of a clay mold and makes it really smooth and shiny, but the loose particles should be brushed out and the mold re-sprayed before the next firing.