The first time you open an epoxy resin TDS — Technical Data Sheet — it’s easy to feel like you’re reading a foreign language. Viscosity, EEW, pot life, Tg, cure schedule… a wall of numbers with no obvious entry point. If you don’t know what each figure actually means in practice, it’s hard to tell whether the product in front of you is the right one for your job.
Most buyers and engineers default to one of two responses: skip to the application rate section, or call the supplier and ask “will this work for what I need?” Neither is wrong. But being able to read a TDS yourself has real advantages — you stop depending on epoxy resin manufacturers to interpret their own datasheets for you at the shortlisting stage, and you go into supplier conversations with a much firmer basis for evaluating what you’re being told.
This guide walks through the main sections of a standard epoxy resin TDS, parameter by parameter — what each one means, what normal ranges look like, and what to watch for when you’re making a selection decision.
1. Product Identification: Start Here Before Anything Else
The opening section of a TDS typically covers product name, grade or model number, product type (liquid or solid, solvent-borne or solvent-free), and component count (one-part or two-part).
It looks basic, but there are a few things worth confirming before moving on.
Component count determines how the product is applied and stored. One-part systems typically require heat to cure and come with specific storage temperature requirements. Two-part systems need to be mixed on-site, and the mix ratio must be followed exactly as written — not estimated. Approximate mixing is one of the most common causes of cure failure in the field.
Product type defines where the product can be used. Solvent-free epoxy systems run at nearly 100% solids content, with minimal VOC emissions — the right call for enclosed spaces or projects with environmental compliance requirements. Solvent-borne products are often easier to apply but carry safety and regulatory risks where ventilation is limited.
If what’s on the TDS doesn’t match what the supplier told you verbally, go with the TDS. Different epoxy resin manufacturers use inconsistent naming conventions for the same product categories — the type classification on the datasheet is more reliable than a product name alone.
2. Appearance and Physical State
Color
Color in epoxy resins is typically expressed as a Gardner rating or an APHA/Hazen value. Lower numbers mean lighter color. For transparent applications — tabletop casting, electronics potting, optical component encapsulation — color is a primary selection criterion. Gardner ≤1 or APHA ≤50 is generally the threshold for what’s called water-white clarity. Industrial corrosion protection and floor coating applications usually have no meaningful color requirements, so you can ignore this parameter for those use cases.
Physical State
Liquid products are used directly or diluted. Solid products — flakes or powder — need to be dissolved or hot-melted before use. High-molecular-weight solid epoxy resins show up in powder coatings and electrocoat paint systems, and they’re handled in a completely different way from liquid products. Make sure you’re reading the right section of the TDS for the form you’re actually working with.
3. Viscosity — the Parameter People Most Often Skip
Viscosity affects how a product applies, how well it wets the substrate, and whether it’ll flow into gaps or stay where you put it. The viscosity figure on a TDS is always tied to a specific test temperature — usually 25°C — and a specific test method (Brookfield spindle, cone-and-plate, etc.).
A rough guide to viscosity ranges and what they’re used for:
| Viscosity Range | Typical Applications |
|---|---|
| <500 mPa·s | Crack injection, wood consolidation, thin impregnation |
| 500–5,000 mPa·s | Self-leveling floors, potting compounds, thin coatings |
| 5,000–30,000 mPa·s | Heavy-body coatings, structural adhesives, trowel application |
| >30,000 mPa·s | Putties, gap-filling compounds, extrusion |
The part that catches people out: viscosity changes dramatically with temperature. The same product can be two to three times thicker at 15°C than at 25°C. Before winter applications, check whether epoxy resin manufacturers publish viscosity-temperature curves for their products. Finding out on-site that the material won’t roll out properly is a fixable problem — but only if you’ve prepared for it.
4. Epoxy Equivalent Weight (EEW) — What Formulation Engineers Look at First
EEW, or Epoxy Equivalent Weight, is the weight of resin in grams that contains one mole of epoxy groups. The unit is g/mol. It’s the foundational number for calculating how much hardener the resin needs.
Lower EEW means higher epoxy group density — more reactive sites per gram of resin. Cured systems with low EEW typically have higher crosslink density, which translates to better hardness, chemical resistance, and glass transition temperature (Tg). The tradeoff is that low-EEW products react faster and leave less room for mixing error.
If you’re working with a pre-formulated two-part system, the mix ratio is already calculated for you based on EEW and hardener chemistry — just follow what’s on the TDS. But if you’re sourcing raw resin and choosing your own hardener, or if you want to substitute a different hardener into an existing formula, you have to start from EEW. Mix ratio deviations above 5% will noticeably degrade cure performance; above 10%, you’re likely looking at a product that won’t cure properly at all.
5. Cure Conditions — The Section That Drives Your Application Planning
Mix Ratio
The TDS will specify whether the ratio is by volume or by weight. Volume ratios are more convenient in the field; weight ratios are more precise. The two are not interchangeable — a 2:1 by volume ratio and a 2:1 by weight ratio represent different actual quantities, and using the wrong basis will throw off the chemistry.
Pot Life / Working Time
Pot life is the window between mixing and gelation — how long you have before the material becomes too viscous to work with. The number on the TDS reflects a specific temperature (typically 25°C) and a specific batch size (often 100g or 500g).
Here’s the detail that trips people up: larger batches generate more heat during the exothermic cure reaction, and that heat accelerates gelation. The pot life on the datasheet is a reference point, not a guarantee for large pours or bulk batches. When mixing at production volume, expect the working window to be shorter — sometimes significantly shorter.
Tack-Free Time
The point at which the surface no longer picks up fingerprints or dust. This is your baseline for when the next process step — overcoating, assembly, handling — can begin.
Full Cure Time
This is almost always longer than it looks. Surface dry in 4 hours does not mean chemically resistant in 4 hours. Full mechanical and chemical properties develop over the complete cure cycle, which might be 24 hours, or it might be 7 days. If you need to test a coating’s chemical resistance, wait until full cure is confirmed. Testing early produces results that have no real meaning.
Cure Temperature
Most standard epoxy systems slow significantly below 5°C and can stall completely. Low-temperature cure formulations exist for cold-weather applications — these need to be specifically selected, not assumed. Elevated post-cure temperatures can substantially raise Tg and final performance. When the TDS provides data for both ambient cure and post-cure, treat the post-cure figures as the material’s actual performance ceiling.
6. Glass Transition Temperature (Tg) — The Thermal Limit You Need to Know
Tg is the temperature at which a cured epoxy transitions from a hard, glassy state to a softer, more rubbery one. When you exceed Tg in service, modulus drops sharply — the material effectively softens. For most structural or protective applications, operating above Tg isn’t acceptable.
Practical reference points: standard industrial flooring and general structural bonding can usually work with Tg in the 60–80°C range. Electronics potting often requires Tg above 120°C, depending on the thermal environment. Aerospace composites and high-temperature industrial applications may require Tg above 180°C — and reaching those values almost always requires a high-temperature post-cure cycle, not just ambient cure.
When a TDS gives both ambient-cure and post-cure Tg values, the gap between them can be 40–60°C. If your application has a meaningful heat resistance requirement, post-cure isn’t optional — it’s the step that gets you to the Tg you actually need.
7. Mechanical Properties
Standard mechanical data includes tensile strength, elongation at break, flexural strength, and compressive strength. These figures come from laboratory test specimens cured under controlled conditions — real-world application performance will generally run somewhat lower.
When using TDS data for design calculations, build in an appropriate safety factor rather than designing to the peak published value.
Elongation at break is worth paying close attention to, especially if it’s not your usual habit. Standard epoxy formulations are brittle — elongation of 1–5% is typical. If the application involves dynamic loads, vibration, or thermal expansion cycling, a standard stiff epoxy may crack over time. You need a toughened or flexible formulation, or a different system entirely.
8. Chemical Resistance
The chemical resistance table in a TDS lists how the cured product performs against common reagents — acids, bases, solvents, salt solutions, oils — usually rated as excellent / good / not recommended, or with quantitative immersion data.
A few things to keep in mind when reading this section:
Chemical resistance ratings are based on fully cured samples. A coating that hasn’t reached full cure will perform significantly worse against chemical exposure than the TDS suggests.
The same resin paired with different hardeners can show meaningfully different chemical resistance profiles. If you’re substituting hardeners or comparing different formulations, don’t assume the chemical resistance carries over.
For specific chemical exposures — a particular solvent concentration, a mixed acid stream, a cleaning agent used in your process — generic resistance tables only go so far. Ask epoxy resin manufacturers for immersion test data specific to your chemical environment. A table rating of “good” for acids doesn’t tell you what happens with 30% sulfuric acid at 60°C for six months.
9. Storage Conditions and Shelf Life
Most people look at this section after receiving the product. It should be reviewed before ordering.
Storage temperature for most liquid epoxy systems runs between 5–30°C. Freezing is a problem — some resins crystallize at low temperatures, and while warming can restore flowability, there can be performance implications if crystallization was severe. Overheating accelerates aging and shortens shelf life. Shelf life ranges from 6 to 24 months depending on the product, and it typically shortens significantly once a container is opened.
For two-part systems, Part A and Part B sometimes have different shelf lives — always work from the shorter of the two. Reputable epoxy resin manufacturers label each component separately with manufacture date and expiry; checking this at goods receipt takes two minutes and prevents the kind of production failure that takes considerably longer to diagnose. First-in, first-out inventory management sounds obvious, but using expired material is a more common source of application problems than most teams expect.
Three Rules for Reading Any TDS
Check the test conditions before comparing numbers. The same parameter measured at different temperatures or with different test methods can produce very different figures. When comparing datasheets across products or suppliers, verify that the test conditions are consistent. Numbers measured under different conditions don’t compare.
Know the difference between typical values and minimum guaranteed values. “Typical” means this is what the product usually achieves. “Minimum” is the performance floor the manufacturer will stand behind. For design and specification purposes, build from minimum values — don’t treat typical figures as commitments.
A TDS is a starting point, not a sign-off. For any application where performance really matters, sample testing and small-scale trials are necessary steps. The TDS narrows the field and tells you whether a product is worth evaluating. It doesn’t replace testing under your actual conditions, with your substrate, in your environment.
For technical support or sample requests specific to your application, contact our team — as experienced epoxy resin manufacturers, we can walk through the datasheet with you and help confirm the right product selection.