Sample Size / Mold Compatibility Checker
Check whether your sample fits in standard mounting molds and get a recommendation for the smallest size that works. Results update as you type; no button to click.
Mount type: compression molds have a fixed 19 mm (0.75″) cavity. Castable cups range from 19–40 mm; the checker uses 30 mm as a typical default. · Clearance: resin gap between the sample and mold wall (and sample top to mold top). 2 mm minimum for routine work; 3 mm or more improves edge retention.
Enter length, width, and height of your sample.
Standard Mounting Mold Sizes
PACE Technologies stocks all common imperial and metric mold sizes for both compression and castable mounting. Compression cavities are a fixed 19 mm (0.75″) deep; castable cups are available in deeper sizes for taller samples or multi-piece mounts.
| Mold Size | Cavity Ø (mm) | Cavity Ø (in) | Category | Typical Use |
|---|---|---|---|---|
| 1 inch | 25.4 | 1.000 | Imperial | The most common size for routine metals work: small parts, fasteners, wire cross-sections. |
| 25 mm | 25.0 | 0.984 | Metric / ISO | European standard, near-equivalent to 1″. Often required for ISO-aligned procedures. |
| 30 mm | 30.0 | 1.181 | Metric / ISO | Slightly larger ISO size; useful for thicker samples or improved edge retention. |
| 1.25 inch | 31.75 | 1.250 | Imperial | A small step up from 1″ when the sample is just a hair too large. |
| 1.5 inch | 38.1 | 1.500 | Imperial | Larger samples, weld cross-sections, or when more resin volume is wanted. |
| 40 mm | 40.0 | 1.575 | Metric / ISO | Larger ISO standard for bulky samples and tube cross-sections. |
| 2 inch | 50.8 | 2.000 | Imperial | Very large samples, gear teeth, multiple small samples in one mount. |
| 50 mm | 50.0 | 1.969 | Metric / ISO | Largest standard ISO size; same use cases as 2″ for metric-aligned labs. |
Clearance & Edge Retention
Clearance is the gap of mounting resin between the sample and the mold wall (and between the sample top and the mold top). The right amount depends on what you need to examine.
The absolute minimum for routine sample prep. Acceptable when the area of interest is at the center of the sample and edges are not critical.
Recommended for most metallographic work. Provides good resin support along the sample perimeter and reduces edge rounding during grinding and polishing.
Used when the edge itself is the area of interest: coating thickness measurements, decarb depth, case-hardening, weld toes. Pair with an edge-retention resin for best results.
Edge rounding is the #1 cause of bad coating-thickness measurements. If you can see the polished surface "rolling over" near the sample edge, you need either more clearance, a harder resin, or both.
Compression vs. Castable Mounting
Both methods produce a mounted sample of the same diameter. The difference is in how the resin cures and what samples each method suits best.
Compression Mounting
Heat-and-pressure cure inside a steel mold (typically 19 mm cavity height). Fast cycle times (5–15 min), excellent dimensional control, and a clean cylindrical mount. Best for routine production work on heat-tolerant samples. Pair with phenolic, epoxy, or diallyl phthalate powders.
Castable Mounting
Room-temperature cure of a liquid resin poured into a reusable cup. Deeper cavities are available (19–40 mm), so it suits taller or oddly shaped samples. The lack of heat/pressure also makes it the right choice for heat-sensitive parts, PCBs, and porous materials.
Tips for Better Mounts
- Section close to the area of interest. A smaller, well-placed sample fits in a smaller mold, saves resin, and grinds faster than an oversized blank.
- Clean and dry the sample before mounting. Oils, cutting fluids, and oxidation prevent resin from bonding to the sample surface, leading to gaps that fill with abrasive and contaminate later steps.
- Mark the orientation. If the analysis direction matters (rolling direction, weld interface, coating side), notch or mark the sample before mounting. Once it's in resin, you lose visual cues.
- Pick a resin that matches the sample's hardness. A soft resin around a hard sample causes edge rounding. For coatings and case-hardened layers, choose an edge-retention or mineral-filled resin.
- Avoid trapping bubbles. For castable resins, pour slowly down the side of the cup. For compression mounting, fill the mold halfway, place the sample, then top it off.
Need More Help?
Learn more about mounting methods, resin selection, and edge retention in our guides, or talk to a PACE applications specialist.
View Mounting Guide ›