Finishing your dice

Finishing is the same job whether you are cleaning up a printed master or a cast copy: take the part from straight-off-the-print (or straight-out-of-the-mold) to flat faces, crisp edges, and an even sheen, without ever touching the engraved numbers. The method below applies to both, so the printing guide and the casting guide both point here.

Inspect before you invest

Look the die over right after washing and curing (or demolding), before any polishing. If you spot a flaw that polishing clearly will not fix - a layer shift, a malformed face, a real void - re-print or re-cast it now rather than sinking time into post-processing a part you will end up tossing. Inspect once more after the first sanding pass, when the surface is even enough to reveal what is actually there. Catching it at either point beats finding it at the end.

Sanding and polishing

• Work up the grits. Sand the masters (and any resin casts) with graded papers - Zona papers are the dice-maker staple - stepping from coarse to fine. Each grit only needs to clear the scratches left by the one before, so do not skip too far between them.
• Keep the faces flat. Lay the paper on a sheet of glass (or any dead-flat surface) and sand the die flat against it, one face at a time, instead of holding the paper in your hand. Hand-sanding rounds the faces and softens the edges - exactly what a die must not do; the glass keeps every face planar and the corners crisp.
• Wet-sand where you can. A little water keeps the dust down (sanding cured resin makes hazardous dust) and stops the paper clogging, for a cleaner cut and a finer finish.
• Finish with a polish (the finest papers, then a plastic polishing compound) for an even sheen. Keep compound out of the engraved numbers so they stay clean and legible.

A master does not need the full polish - a cast does. If the master is only going to make a mold, you finish every cast to a polish anyway, so a mirror shine on the master is wasted effort. Take the master through the coarser cleanup grits only - far enough that the faces are flat, the edges crisp, and the surface even and scratch-free so it releases cleanly from the silicone - and save the fine papers and compound for the cast. (The exception is a master you intend to use as the die itself, with no mold: then take it all the way.) On a printed master, that cleanup pass also clears the small witness marks left where the support fins met the edges, and crisps the corners back up.