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Jesmonite AC730 (Stone Casting) for Shallow Tray / Coaster Mold Calculator

Pre-loads specific gravity (1.85) and 5:1 mix ratio to calculate exact Part A & Part B weights with cup scraping buffer.

Calculated Benchmark Answer

A standard Shallow Tray / Coaster Mold (20 × 15 × 2 cm minus 150 cm³ master) requires 899g (31.71 oz / 1.98 lbs) of Jesmonite AC730 (Stone Casting). Mix 749.3g Part A with 149.9g Part B (8% buffer included).

Casting Material & Volume Mode

SG: 1.85

Pre-loads specific gravity and 5:1 ratio by weight.

tray

Geometry determines the container-volume formula. Use water displacement when the cavity is irregular.

cm(7.9 in)
Min: 2 cm31%Max: 60 cm
cm(5.9 in)
Min: 2 cm27%Max: 50 cm
cm(0.8 in)
Min: 1 cm3%Max: 30 cm
cm³(5.1 fl oz)
Min: 0 cm³3%Max: 5000 cm³

Volume displaced by your master object inside the box.

%
Min: 0 %40%Max: 20 %

Compensates for resin clinging to mixing paddles and cup walls (8% recommended).

Preset Values: Buffer Presets
Graduated Mix Volume Schematic
RATIO 5:1
25%50%75%100%PART A [BASE]749g26.43 oz+25%50%75%100%PART B [CATALYST]150g5.29 oz
PART A: 749.3gJesmonite AC730 (Stone Casting)PART B: 149.9g
Mold Cavity Cross-Section
NET POUR: 450 cm³
MASTER OBJECT-150 cm³ Displaced1.5cm Wall1.5cm WallContainment: 20cm L × 15cm W × 2cm H
COMPOUND: Jesmonite AC730 (Stone Casting)•MASTER: 150 cm³•POUR: 450 cm³
Total Batch RequiredKEY RESULT
899.1grams
31.71 oz (1.98 lbs)

Includes 8% waste buffer at SG 1.85

Part A (Base)
749.3g
26.43 oz

Ratio part: 5

Part B (Catalyst)
149.9g
5.29 oz

Ratio part: 1

Mold Cavity Volume
450cm³ / mL
15.22fl oz

Net volume before buffer

Verified Casting Kit Reference Spec

Order Jesmonite AC730 (Stone Casting) Kit

High-tear strength Jesmonite AC730 (Stone Casting) with verified 5:1 ratio. Ideal for bubble-free casting.

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Jesmonite AC730 (Stone Casting) vs Alternative Casting Compounds

Compare specific gravities, mix ratios, working times, and cure speeds across casting compounds.

Material / SpecificationSpecific GravityMix RatioPot LifeDemold Time
Jesmonite AC730 (Stone Casting)ACTIVE1.855:1 (weight)15 min4 hrs
RTV-2 Platinum Silicone (Smooth-On Mold Star 15/30)1.071:1 (weight)30 min6 hrs
RTV-2 Tin Cure Silicone (Condensation Cure)1.1210:1 (weight)45 min12 hrs
Jesmonite AC100 (Eco-Resin)1.752.5:1 (weight)12 min2 hrs
Deep Pour River Epoxy (2:1 Ratio)1.112:1 (weight)90 min48 hrs
Table Top & Art Epoxy (1:1 Ratio)1.081:1 (weight)25 min12 hrs

Step-by-Step Mix Ratio Derivation: Jesmonite AC730 (Stone Casting)

How displacement volume, specific gravity, and ratio split combine into final scale weights.

Step 1: Calculate Net Mold Cavity Volume450 cm³ (mL)
Formula: V_net = (L × W × H)_box - V_master
Calculation: (20 × 15 × 2) - 150 cm³ = 450 cm³ (mL)

Calculates the empty fluid cavity by taking the gross 600 cm³ tray containment volume and deducting the 150 cm³ displaced by the master model.

Step 2: Calculate Total Batch Weight with 8% Buffer899.1 grams
Formula: W_batch = V_net × SG × (1 + Buffer_pct / 100)
Calculation: 450 cm³ × 1.85 × 1.08 = 899.1 grams

Multiplies fluid volume by the specific gravity of Jesmonite AC730 (Stone Casting) (1.85 g/cm³) plus an 8% buffer for cup scraping and pouring loss.

Step 3: Divide into Part A and Part B by Mix RatioPart A: 749.3g | Part B: 149.9g
Formula: W_A = W_batch × (R_A / (R_A + R_B))
Calculation: 899.1g × (5 / 6) = Part A: 749.3g | Part B: 149.9g

Distributes batch mass according to the exact 5:1 ratio by weight.

MetriFab Precision GuaranteeFormulas cross-verified against Blum, Smooth-On, Polymaker, and eSun technical data sheets.
Zero-Lag SSG

Engineering Specifications & Troubleshooting Guide: Jesmonite AC730 (Stone Casting)

Factory-tested parameters, common failure modes, and workbench best practices.

Maker Pro Tips
  • Formulated with decorative stone aggregates for outdoor architectural facades and garden planters.
  • Acid-etch the cured surface with 5% brick acid or vinegar to expose shimmering granite/sandstone aggregates.
Most Critical Mistake to Avoid

Allowing direct outdoor water exposure before the complete 7-day moisture cure is achieved.

Recommended Machine Settings
mixing TechniqueMechanical paddle mixer; fold slowly to preserve aggregate texture.
degassing RequiredNo
demold NoteDemold after 4 hours. Keep under plastic wrap for 24 hours to cure.

Frequently Asked Questions: Jesmonite AC730 (Stone Casting)

Mix ratios, degas guidelines, cure times, and mold making tips.

Q1What is the mix ratio of Jesmonite AC730 (Stone Casting)?
Jesmonite AC730 (Stone Casting) has a mix ratio of 5 Part A to 1 Part B by weight. Always weigh both components on a digital scale for maximum cure integrity.
Q2How much Jesmonite AC730 (Stone Casting) do I need for a Shallow Tray / Coaster Mold?
For a standard Shallow Tray / Coaster Mold with 20 × 15 × 2 cm outer containment, you will need approximately 899 grams (749.3g Part A and 149.9g Part B) including an 8% waste buffer.
Q3How long before I can demold Jesmonite AC730 (Stone Casting)?
Jesmonite AC730 (Stone Casting) has a pot life (working time) of 15 minutes and can safely be demolded in 4 hours at room temperature (23°C / 73°F).

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Related Master Reference Guides & Lookup Charts

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Specific Gravity
Silicone & Resin Specific Gravity Chart
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Batch Math
Jesmonite AC100/AC730 Mix Ratio Guide
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