Smooth-On
EpoxAcast™ 690
- Type
- Casting
- Data sheet revision
- 040925PA (code printed on document)
- Sources checked
- 2026-09-30
- Page status
- Published October 3, 2026
A clear casting epoxy mixed by weight only (100A:30B). Smooth-On's bulletin limits pours to 3/8 in with the standard method or 3/4 in with fan cooling, with a 5 hour pot life.
Published values
Copied as printed, with test conditions where the manufacturer gives them. Tags link to the source document.
| Mix ratio by volume (A:B) | not published |
|---|---|
| Mix ratio by weight (A:B) | 100A : 30B by weightTDS |
| Maximum pour depth per layer | 3/4" (1.9 cm) fan-cooled; 3/8 in. (0.95 cm) standard castingTDSfan-cooled casting method (box fans over the surface), poured at 70°F/21°C; standard casting method maximum is 3/8 in. (0.95 cm). |
|---|---|
| Minimum pour depth | not published |
| Maximum mass or volume per pour | maximum batch size of 20.8 lbs. (9.43 kg.) per pourTDSrecommended maximum batch size per pour (by weight); larger batches may cause high exotherm |
| Recommended temperature | 70°F/21°CTDSrecommended ambient temperature for use (single value, not a range); cooler environments recommended for large mass pours |
| Pot life | 5 HoursTDSASTM D2471; mass- and mold-dependent |
|---|---|
| Working time | not published |
| Time between pours | allow previous layer to fully cure before pouring subsequent layersTDSno interval in hours is published |
| Recoat window | not published |
| Tack-free | not published |
| Demold | not published |
| Full cure | 24 Hours (standard casting method); 36 Hours (fan-cooled casting method)TDSpublished as 'Cure Time' (hard, cannot be penetrated with a fingernail), standard casting method, 3/8 in. at 70°F/21°C; fan-cooled: 36 hours; published physical properties were measured after 7 days at 70°F |
| Mixed viscosity | 280 CPSTDSmixed, ASTM D2393 |
|---|---|
| Specific gravity or density, Part A | 1.0 – 1.2SDSSDS Part A (No. 36A) section 9, Specific Gravity (H2O=1, at 4 °C); published as a range |
| Specific gravity or density, Part B | 0.95SDSSDS Part B (No. 36B) section 9, Specific Gravity (H2O=1, at 4 °C) |
| Specific gravity, mixed | 1.10 g./c.c.TDSmixed, ASTM D1475; labelled 'Specific Gravity - Mixed; g./c.c.' |
| Density, mixed | not published |
| Hardness | 80 Shore DTDS |
What the numbers mean for a pour
Pours needed with a limit of 3/8 in per pour, the strictest of the limits the documents give. Worked out with the layer planner.
| Total thickness | Pours | Earliest start of last pour | Notes |
|---|---|---|---|
| 1 in (25 mm) | 3 | not published | – |
| 2 in (51 mm) | 6 | not published | – |
| 3 in (76 mm) | 8 | not published | – |
| 4 in (102 mm) | 11 | not published | – |
The data sheet describes the wait in words only (“allow previous layer to fully cure before pouring subsequent layers”), so no time is calculated.
What the manufacturer says
Paraphrased from the manufacturer’s documents.
Other notes
- Parts must be weighed on an accurate digital gram scale; Smooth-On says not to measure by volume.TDS
- Castings 1/4 in. (0.64 cm) thick or less cure more slowly.TDS
- Smooth-On says not to vacuum-degas EpoxAcast 690 or 692.TDS
- The TDS advises a well-ventilated area, a NIOSH-approved respirator, safety glasses, long sleeves and rubber gloves.TDS
Layering
- With the standard (no-fan) method the maximum casting thickness is 3/8 in. (0.95 cm) at 70°F.TDS
Temperature
- Cooler rooms are recommended for large-mass pours.TDS
Heat
- Cups or containers hotter than 120°F/49°C will damage the cured surface.TDS
- Heat deflection temperature is 115°F/46°C when cured at room temperature.TDS
UV and color
- Unpainted castings yellow under UV light or heat above 100°F/38°C.TDS
Coverage
- Specific volume of the mix is 25 cu. in. per lb.Page
Safety data sheet summary
Signal word: DangerSDS
Part A hazard statements
- H315 Causes skin irritation.
- H317 May cause an allergic skin reaction.
- H319 Causes serious eye irritation.
- H411 Toxic to aquatic life with long lasting effects
Part B hazard statements
- H314 Causes severe skin burns and eye damage.
- H318 Causes serious eye damage.
- H412 Harmful to aquatic life with long lasting effects
Protective equipment
- Wear liquid-tight gloves such as butyl rubber, neoprene or PVC.
- Wear safety glasses with side shields.
- Where a risk assessment calls for it, use an approved air-purifying respirator with suitable cartridges as a backup to engineering controls.
Ventilation
- With adequate local exhaust ventilation, respiratory protection is not normally required.
A summary, not the full SDS. Read the SDS for both parts before use and follow its first-aid section in case of exposure. This is not medical advice.
Not published
The documents listed below give no value for: Mix ratio by volume (A:B); Minimum pour depth; Working time; Recoat window; Tack-free; Demold; Density, mixed. We leave these blank rather than estimate them.
Use this product in a calculator
Sources
- Smooth-On. EpoxAcast™ 690 and 692 Deep Pour Clear Castable Epoxy Resins (Technical Bulletin, covers both products) (TDS). Document revision: 040925PA (code printed on document). Accessed September 30, 2026.
- Smooth-On. Safety Data Sheet EpoxAcast 690 Clear, Part A (SDS No. 36A) and Part B (SDS No. 36B) (SDS). Document revision: Part A: October 25, 2023 Version 4.0; Part B: January 3, 2022 Version 5.0. Accessed September 30, 2026.
- Smooth-On. EpoxAcast™ 690 Product Information (Page). Accessed September 30, 2026.