| Polymer Type | VAE, VAE/VeoVa, acrylic, or styrene-acrylic systems are commonly used. | Product technical documentation; FTIR may be used for polymer identification. | The polymer chemistry influences adhesion, flexibility, water resistance, weatherability, and compatibility with mineral binders. | Use VAE-based grades for general cementitious mortars; consider acrylic or styrene-acrylic grades when improved weathering or water resistance is required. |
| Polymer Solids Content | Usually about 98–100% for a properly dried redispersible powder. | ISO 3251 or an equivalent loss-on-drying method. | Higher and more consistent solids generally improve dosage accuracy and reduce variation between batches. | Compare solids on the same test basis and check the moisture limit separately; do not compare nominal values produced by different methods. |
| Glass Transition Temperature (Tg) | Common grades may range approximately from −20°C to +20°C, depending on chemistry. | Differential scanning calorimetry, typically ISO 11357-2. | Tg affects the balance between flexibility, hardness, blocking resistance, and low-temperature film formation. | Choose lower-Tg grades for flexible tile adhesives, renders, and repair mortars; choose higher-Tg grades when hardness and blocking resistance are more important. |
| Minimum Film Formation Temperature (MFFT) | Common commercial grades are often designed for approximately 0–15°C, although the actual value varies by polymer. | ISO 2115 or an equivalent MFFT procedure. | The polymer must form a continuous film under the expected curing and application temperature. | For cold-weather application, select a grade with an MFFT below the expected substrate and ambient temperature, while verifying early-strength development. |
| Redispersibility in Water | The powder should redisperse rapidly into a uniform milky dispersion without persistent coarse particles or gel-like lumps. | Controlled laboratory dispersion test with visual evaluation and sieve residue measurement. | Poor redispersion can cause weak spots, pinholes, inconsistent adhesion, and uneven water resistance. | Compare samples using the same water quality, mixing energy, temperature, and dispersion time. A practical screening period is 5–10 minutes. |
| Particle Size and Sieve Residue | Powders are generally fine and free-flowing; sieve residue should be low and consistent according to the supplier specification. | Laser diffraction, ISO 13320, plus a specified sieve-residue method. | Particle size affects dispersion speed, powder handling, surface appearance, and the uniformity of the polymer film. | Avoid excessive coarse particles, which may indicate agglomeration, poor storage stability, or inadequate spray drying. |
| Bulk Density | Many products fall approximately within 400–700 g/L, depending on formulation and spray-drying conditions. | ISO 8130-2 or an equivalent bulk-density method. | Bulk density affects silo capacity, packaging weight, feeding accuracy, dust behavior, and volumetric dosing. | Compare products by weight rather than volume and confirm that the density is compatible with the existing dosing equipment. |
| Ash Content | Often approximately 5–20%, depending on protective colloids, mineral anti-blocking agents, and product design. | Controlled ignition or thermogravimetric analysis, with the test temperature clearly stated. | Ash content influences the effective polymer dosage and may affect flexibility, water demand, and film properties. | Do not treat low ash as automatically better; compare ash together with polymer solids, performance, and the intended mortar formulation. |
| Tensile Strength and Elongation | Values vary widely with polymer type, film conditioning, and test formulation; flexibility is normally assessed by elongation and tensile behavior together. | ISO 527 or ASTM D638 on a standardized polymer film. | These properties indicate whether the polymer film can accommodate movement, shrinkage, and thermal stress. | For crack-bridging or deformable systems, prioritize adequate elongation and recovery rather than tensile strength alone. |
| Adhesion Strength in the Final Mortar | The required value depends on the application standard; tile adhesives, renders, and repair mortars have different acceptance criteria. | EN 1348, EN 1015-12, or the relevant local product standard. | Adhesion is the most direct indicator of whether the powder performs in the actual cementitious formulation. | Test the complete formula on concrete, cement board, ceramic tile, or the actual substrate instead of relying only on powder-level data. |
| Water Resistance and Capillary Water Absorption | Lower water absorption is generally preferred for exterior renders, waterproofing-related mortars, and wet-area applications. | EN 1015-18, EN 1062-3, or an application-specific water-absorption method. | Water resistance affects durability, freeze–thaw performance, stain resistance, and long-term bond retention. | Evaluate water absorption after the required curing period and use the same cement, filler, water-to-binder ratio, and polymer dosage for all candidates. |
| Open Time and Wet Adhesion | Longer open time is beneficial for large-format tiles and difficult site conditions, but the required level depends on formulation and climate. | EN 1346 for tile adhesive open time; wet adhesion should be tested according to the applicable standard. | These properties determine installation flexibility and the ability to maintain bond after surface drying or water exposure. | Select a grade that provides sufficient open time without creating excessive sag, slow setting, or poor early strength. |
| Anti-Sag and Slip Resistance | The finished adhesive should meet the slip limit required by the relevant product classification. | EN 1308 or the applicable tile-adhesive classification method. | Slip resistance affects vertical installation, tile alignment, labor efficiency, and application safety. | Check the powder together with cellulose ether, cement, sand grading, and water content because anti-sag performance is formulation-dependent. |
| Compatibility with Cement and Additives | The mix should remain homogeneous and show predictable setting, workability, and strength after storage and curing. | Pilot formulation testing, setting-time measurement, rheology, and stability observation. | Incompatibility can cause lumping, excessive air entrainment, delayed setting, poor water retention, or loss of adhesion. | Run a laboratory trial using the actual cement source, fillers, cellulose ether, defoamer, pigments, and mixing equipment before approval. |
| Storage Stability and Caking Resistance | The powder should remain free-flowing and redisperse consistently within the stated storage period when kept dry and sealed. | Accelerated storage evaluation, flowability test, sieve residue, and redispersion check. | Moisture pickup and caking can reduce dosing accuracy and cause inconsistent final-mortar performance. | Review packaging, recommended storage temperature, shelf life, and performance after opening or partial-bag use. |
| Dust, Safety, and Sustainability Profile | Prefer low-dust handling grades, documented occupational-safety information, and verified environmental data where required. | Safety Data Sheet, technical documentation, dust-emission screening, and applicable environmental declarations. | Dust control supports worker safety, cleaner production, and more reliable handling during bag emptying and automated dosing. | Compare dust behavior, packaging waste, bio-based content claims, VOC information, and third-party declarations without compromising technical performance. |
