HOW WE MAKE
PETROGRIPS

RAW MATERIALS

We use crushed granite, crushed sandstone, and river sandstone. The granite we use is a special rock known as "Black Granite" in the dimension stone trade. This stuff is incredibly strong - stronger than plastic. Black granite is so strong and uniform in it's physical properties that it was used by the Bureau of Standards for weights and measures. One of the more exotic uses for this material was as dummy warheads in nuclear missiles.

GRINDING

Modular holds need a flat back. This is perhaps the most difficult and most important step in making holds out of rock. We use a very large nasty machine with very large nasty diamonds that grinds away rock like it was made out of wood. This gives us a lot of leeway in choosing the final aspect of the hold - for instance we can make some really radical incuts which are great for those steep walls or beginning climbers.

COUNTERSINKING - GLUING

Modular holds need a countersink hole to fit the head of the mounting bolt. We use a secret process that makes perfect countersink holes even on an angled surface. We don't use a drill bit for this and don't recommend trying this at home - it's dangerous. We also glue in a stainless steel washer at the bottom of the countersunk hole. The washer insures the stresses from tightening the mounting bolt are evenly distributed throughout the rock. We use stainless washers while the plastic hold companies use zinc plated washers. After 3-4 years of outdoor use a plated washer is a pile of rust - no big deal as most plastic holds won't last this long outdoors. Our holds are far more durable and will last forever so the washer needs to last forever.

DRILLING - MILLING

We drill a hole through the glued-in washer and the rock. Our micros and some small sandstone holds get a 3-layer fiberglass/epoxy backing. This prevents shear stresses from cracking these narrow holds if over tightened on a irregular surface. ALL of our holds get a treatment in our BALL MILL. This acts like a giant rock tumbler and performs two functions. First, the ball mill treatment rounds off any sharp edges and corners. This artificially "weathers" the rock so it feels like a piece of rock on a real cliff. It also makes the holds comfortable to hold onto. The second reason for the ball mill treatment is to weed out any rocks with cracks or weaknesses. The rock we use is so strong it will only fail if there is some pre-existing crack or fracture in the rock. The ball mill treatment is so violent it quickly destroys any rock with cracks. The holds that survive the ball mill are way strong.