This Prehistoric GBD was in pretty decent shape, with some bowl-top build-up and a mildly oxidized stem. GBD Prehistorics usually have polished bowl tops that survive even the worst build-up abuse and restore beautifully. This one is shape 9486.
I used my Pipenet reamer set to remove the cake. I used a wet cloth and then a worn piece of scotch-brite pad to remove the build-up on the bowl top. The top was finished with a worn piece of 8,000 grit micromesh. All of the build-up came off, without breaking the stain and it polished beautifully. I soaked the bowl with alcohol and sea salt. The interior of the bowl was in excellent condition.
I put a dab of grease on the GBD rondell and soaked the stem in a mild Oxy-Clean solution. Mounted to the bowl, I used 800, 1500 and 2000 grade wet paper to remove the oxidation. The stem was finished with 8,000 and 12,000 grade micromesh. I wrap the sanding papers around a popsicle stick to keep the square shank edges sharp. The stem was buffed with White Diamond and Meguiars Plastic Polish.
The bowl top was polished with White Diamond and several coats of Carnuba wax. The blasted part of the bowl was hand waxed with Halycon wax.
Below is the finished pipe.