Gloss, yield, pot life, VOCs, safety data sheet: here's the vocabulary of technical data sheets, explained simply. The official values are always those found on the product's data sheet.

Summary

• Film appearance (gloss)
• Shelf life
• Substrate conditions and temperature
• Polymerization time
• Density (specific weight)
• Volume dry residue (VDR)
• Film thickness
• Practical yield
• Mixing ratios (2K)
• Induction time
• Pot life
• VOCs
• SDS and technical data sheet
• Stain and opaque paint
• Tint and ready-mix
• Washability

Film appearance (gloss)

Gloss values are measured according to ISO 2813 (equivalent to ASTM D 1471 and DIN 67530), in gloss units. The ranges below are a common guideline; the exact rating of a product is shown on its datasheet.

• Matte : 0–10 gloss
• Satin-matte (eggshell): 10–20 gloss
• Satin/semi-gloss : 20–45 gloss
• Glossy : 45–75 gloss
• Very glossy : 75–100 gloss

More details: Degree of gloss .

Shelf life

The period during which the product remains usable in a new, unopened container, generally stored between +5°C and +30°C (protected from frost and excessive heat). Beyond the date indicated on the product sheet, check the product before use (appearance, mixture, application on a test).

Do not confuse with pot life , which only concerns the mixture that has already been catalyzed.

Substrate conditions and temperature

The surface must be clean, dry, degreased and prepared according to the instructions (sanding, rust removal, descaling, etc., depending on the material).

To limit condensation on the fresh film, the temperature of the substrate must remain at least 3°C above the dew point .

Example at 70% relative humidity

Metal that has cooled overnight can remain below the dew point even if the air has already warmed up. Wait for the surface to warm up before painting.

Polymerization time

The time it takes for the film to reach the chemical and mechanical resistances for which it was formulated. Often 7 to 10 days at +20°C. Before this time, the film may already be dry to the touch without yet having reached full strength.

Density (specific weight)

Mass of one liter of product (kg/l). Data sheets often indicate a tolerance of approximately ±0.05 kg/l. Useful for converting volume to weight (and vice versa) for dosing or shipping.

Volume dry residue (VDR)

Percentage of volume remaining after evaporation of solvents/water. Measured according to ISO 3233 (equivalent to ASTM D 2697 and DIN 53219). This value relates the applied wet thickness to the resulting dry thickness, and therefore to the theoretical yield.

Film thickness

A distinction is made between wet thickness (immediately after application) and dry thickness (after drying). Respect the prescribed dry thickness to within approximately ±10%: too thin, the film provides poor coverage and protection; too thick, there is a risk of runs, slow drying, or fragility.

Conversion formulas:

• Dry thickness = wet thickness × RSV % / 100
• Wet thickness = dry thickness × 100 / RSV %

Practical yield

The theoretical yield is calculated from the RSV and the target dry thickness. The practical yield is lower: roughness, absorption, spray gun losses, weather conditions.

Common marking on smooth metal: approximately 70% of theEoric, sometimes 40–50% on small or irregular pieces. On wood, plaster or concrete, absorption and smoothing of the pores make any precise calculation impossible without testing on site.

Mixing ratios (2K products)

A two-component product (paint + hardener) is mixed according to the ratio on the data sheet, either by weight or volume as indicated. Rinse the hardener container with a small amount of the specified thinner and add this rinse water to the mixture to avoid under-mixing.

Do not substitute a hardener from another range or brand: the ratio is calculated for the intended base/hardener combination.

Induction time

Waiting time between mixing the two components and starting application. Depending on the product and temperature, this can range from a few minutes to 15–20 minutes. It allows the mixture to homogenize before application.

Pot life (duration of use after catalysis)

The pot life during which the 2K mixture remains workable. Often 4–5 hours at +20°C; this decreases as the temperature rises. Some express hardeners have a very short pot life: always reread the data sheet for the specific hardener being used. Once the pot life has expired, do not apply the mixture.

VOCs

Volatile organic compounds. The product information sheet generally indicates a value in g/l and sometimes a percentage. In Switzerland, a VOC tax may apply depending on the product and packaging; the amount shown on the product page in the shop is indicative and already included in the price when mentioned.

Safety Data Sheet (SDS) and Technical Data Sheet (TDS)

The technical data sheet describes the application: substrates, dilution, thickness, drying time, and coverage. The SDS describes the hazards, storage, PPE, and emergency procedures. These are two separate documents. If you have any doubt about a mixture or its use, the product data sheet for the product being sold is the authoritative document.

Stain and opaque paint

A wood stain allows the wood grain to show through (the film varies in thickness depending on the product). A paint or enamel, on the other hand, completely covers the surface. These are not the same systems, nor do they require the same maintenance.

See also: Difference between covering products and glazes and How to properly apply a wood stain .

Tint and ready-mix

A ready-mix is a factory-made color, delivered ready to use. A machine-mixed color (NCS, RAL, Sikkens 5051, Cetol, etc.) is mixed in the store with a base. The color code and base must correspond to the chart provided for that product; the same NCS or RAL reference does not always produce an exact match from one grade to another. The degree of gloss, the acceptable tolerance margin, etc., can mean that the same reference may have a slight difference from one product to another.

Color charts: Online color charts .

Washability

For wall paints, wash resistance is often expressed by a wet abrasion class (EN 13300 standard). Class 1 = the most resistant.

Detail: Washability according to resistance to wet abrasion .