Practice material — exactly what to buy, and where to get the real thing

Why bone meal fights you

Real cremated remains are calcined bone — bone fired hot enough (~1,400–1,800°F) to burn off everything organic, leaving only the mineral (calcium phosphate), then ground to a coarse, sandy grit. Off-white to gray, dry, inert.

Bone meal still carries protein, fat, and moisture. It's greasy and biologically active, so it fights the resin — discoloring, staying tacky, reading wrong in the bead. You've been fighting the medium, not your technique. The fix is to switch to the pure mineral (bone ash) and give it the right texture.

What to buy

Two ingredients plus one tool: a fine calcium-phosphate flour (pottery bone ash — same mineral as real cremains) as the body, and a coarse white calcium grit to give it the speckled, sandy texture. You blend them yourself. Total kit ≈ $35.

Why aragonite (or oyster shell), not "poultry grit": generic poultry grit is crushed granite — gray and glassy. Aragonite reef sand is bright-white calcium carbonate pre-graded to ~1–2 mm, so it drops straight into the blend with no sieving. White oyster shell is the same mineral family and cheaper, but you sieve it to size. Either is the right color; skip granite grit.

How to mix it

1. Grade the grit first (skip this if you bought aragonite — it's already ~1–2 mm). For oyster shell: pour it into the coarsest strainer over a bowl and shake. Anything too big (>~2 mm) gets set aside or hand-crushed. Then sift out the dust through the finest strainer. Keep the middle fraction — grains roughly 0.5–2 mm.
2. Start at 80/20 by volume — 4 scoops bone-ash flour : 1 scoop graded grit. Measure by scoop, not scale (the two have very different densities). Mostly-fine body with clearly visible speckle — what coarse-ground cremains look like.
3. Dry-mix flour and grit thoroughly before any resin touches it, so the grit stays evenly suspended.
4. Tune it. More grit = coarser feel, heavier speckle; less = smoother and chalkier. Make three test mixes — 85/15, 80/20, 70/30 — and cast a pearl from each to pick the look you want to standardize.
5. Mix into resin as usual. Keep your current medium-to-resin ratio (~227 g medium per batch, ~33 g / 2 in pearls). The grit is still calcium filler by volume — it doesn't change your resin math.

How much to buy

• Each batch = 227 g of medium. At 80/20 that's ~180 g bone ash + 45 g grit per batch.
• For ~8–10 practice batches: 5 lb bone ash + one 5 lb bag oyster shell. Leaves margin for re-grading losses and texture tests.
• Total: ~$12 bone ash + $7 grit + $15 sieves ≈ $35.

This blend is your practice / technique medium — for dialing in mix ratio, forming, and finish. When you move to real material, you swap in donated pet cremains at the same volume; handling, resin ratio, and forming stay identical.

Where to get real pet cremains — local, with numbers

These are real pet crematories in your area (Marietta / Cobb / Metro Atlanta). Call the Call first ones — they're cremation-focused, so you're not a competitor. Ask whether they'll let you have unclaimed / communal cremains they'd otherwise scatter, or set up owner-consented donations, for product R&D — you'll sign a simple release and cover their handling. Keep it a donation, not a purchase.

What to say when you call: "I run a Georgia memorial-keepsake company, Custom Cremations. I'm developing a product and need practice material that behaves like real cremated remains. Would you be open to donating unclaimed or communal pet cremains you'd otherwise scatter — or arranging owner-consented donations — for R&D? I'll sign a release and cover your handling." The cremation-only shops are your best odds.

Optional: the higher-fidelity route (needs a kiln)

If you get kiln access, you can skip the grit-blend and make a near-exact analog: take clean, degreased butcher/soup bone, calcine it to bisque temperature (~1,650–1,830°F / cone 08–04) until chalk-white, cool, then grind and screen to a coarse-sand grade. That gives real calcium-phosphate grains in the exact color and texture of processed cremains — no carbonate grit needed. More work; keep the bone-ash-plus-oyster-shell blend as your default and treat this as an upgrade.

Sources

Bone ash / tricalcium phosphate — The Ceramic Shop · Seattle Pottery Supply · Digitalfire (chemistry)
Cremains composition & process — A Good Goodbye · Cremation.green
Local crematories — Honor My Pet · Faithful Companion · Paws, Whiskers & Wags · Atlanta Pet Cemetery