Charlie already answered your question but here is what i learned back in the cavalery school in Switzerland and it became part of my lectures to bored college students here in the USA. This is where i get it from!
The Horse Shoe Barn
the paper has turned yellow: Borium is tungsten carbide shaped into a soft steel rod 1/8" to 1/4" thick. To apply borium to a shoe, you need a set of acetylene welding torches, welding glasses, welding gloves, a safe work area, and the skill and training to weld. To follow these instructions, you have to already know how to weld. Shape the shoes to fit the hooves, just as you would for summer shoeing. Before you nail the shoes on, add the borium as follows: Stack the shoes on top of each other, which helps avoid wasting heat. As you add borium to the top shoe, the next shoe down heats up, as well.
Work on one spot at a time. Add a spot of borium to each heel and two spots at the toe, just ahead of the first nail hole. Get the spot up to welding heat and heat the borium rod at the same time. When the steel begins to puddle, pull the welding tip away, adding borium as you go back and forth with the welding tip and the borium.
For a little traction, make a short spike; for more traction, make a taller spike. Adding borium takes a good amount of skill and practice, but the flexibility of its placement on the shoe and the excellent traction it offers make borium a good choice.
