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- Provide Alumogrit® or Ferrogrit® type _____, size____, safety treads/nosings as manufactured by Wooster Products Inc. for interior and exterior stairs.
- Abrasive shall be #20 virgin grain Aluminum Oxide (AL2O3) abrasive, integrally cast into the walking surface to a minimum depth of 1/32 inch.
- Safety nosings up to 6″ deep with cross-hatched surface being installed into wet concrete shall have a “Feature Strip” (Trademark 3571602) along the back edge.
- Concealed type anchors shall be slotted rivet type, integrally cast into the body of the nosing a minimum of 3/8 inch. (Not mushroom type)
- Cast metals used shall conform to the following specification:
- Alumogrit® (Abrasive cast aluminum): No. 43 secondary ingot; low copper content; corrosion resistant.
- Ferrogrit® (Abrasive cast iron): Class 20 iron; high silicon; machinable; hypereutectic.
- Any holes or countersinks shall be machine made. Screwheads shall not protrude above tread surface.
- All metal types shall have shot blasted finish; Ferrogrit® treads shall have one coat shop black paint.
- Cross hatching and fluting shall be 1/16 inch deep minimum and shall be clean and well defined.
- Nosings shall terminate not more than 4″ from ends of steps for poured concrete stairs; for concrete filled steel pan stairs, nosings shall be full length of steps less 1/8 inch clearance.