PRESTO BLACK BST4 Brush-On Blackener
PRESTO BLACK BST4 is a liquid brush-on blackener for all iron and non-stainless steels. Applied at room temperature by swab-on or spray techniques, the BST4 reacts quickly and produces a non-dimensional black finish in 30-90 seconds. The finish can be sealed with a protective oil and is suitable for use on precision tooling and machine components. Or, the black finish can be highlighted to produce a pleasing distressed or antique pewter type finish on decorative metalwork, architectural trim or hand-forged items.
In short, the surface must first be thoroughly cleaned of all oil and excess scale. The black finish is then applied, rinsed, dried and sealed with a topcoat appropriate to the end use of the article:
- CLEAN the metal surface, using a solvent that does not leave a Use alcohol, acetone, lacquer thinner or equivalent (Do not use mineral spirits or kerosene).
- REMOVE OXIDES, if necessary, by bead blasting, or use other abrasive cleaning methods, such as buffing with Scotchbrite abrasive pads or flap wheels.
- APPLY PRESTO BLACK BST4 solution to the metal surface by brush, swab or spray techniques (using a plastic pump sprayer). For best results, apply a thin film of solution on the surface, and then re-apply a few more times during the course of the reaction in order to “replenish” the supply of chemicals working on the A light-duty flooding technique usually works best. For large surfaces, apply the BST4 solution with a wide applicator or with a pump sprayer to facilitate wetting a larger area in a few seconds. Continue application until a uniform gray/black finish is achieved. DO NOT LET THE BST4 SOLUTION DRY ON THE SURFACE, or flash rusting can occur.
- STOP the REACTION by sponging the surface with water to remove blackening residues. Note: Flash rusting can occur easily, at times. To avoid the flash rusting, have a baking soda solution pre-mixed and ready to apply as a second rinse (mix 2 tablespoons per gallon of warm water) to neutralize the This will inhibit the rusting tendency.
- FORCE DRY the surface with compressed air or warm air to speed
- SEAL the surface with a topcoat appropriate to the use of the article: Tooling/machine parts can be sealed with a water-displacer, such as DRI TOUCH AMBER IRP2. Decorative surfaces can be highlighted, if desired, with Scotchbrite pads, to produce a distressed or antique finish, then sealed with a clear, satin lacquer. Or, for light-duty, indoor pieces, use paste wax.
Before Using This Product – Please Read, Understand and Follow all the Precautions shown on the Product Label and on the Safety Data Sheet.