Sikalastic®-641 Lo-VOC
waterproofing systems
Sikalastic®-641 Lo-VOC is a cold applied, highly elastic, aliphatic, single component, low-odor, low-VOC moisture-triggered polyurethane resin designed for easy application as part of Sikalastic® RoofPro roofing/waterproofing systems.
- Proven technology with over 30 year track record
- Single component - no mixing and ready to use
- Fully reinforced with highly conformable Sika Reemat or Sika Fleece
- Moisture triggered chemistry that is rapidly weatherproof after application
- Resistant to ponding water
- Low VOC formula - low Odor
- Highly elastic and crack bridging
- Seamless and fully adhered
- Vapor permeable
- UV resistant and non-yellowing
- Abrasion and chemical resistant
- Adheres to most common construction materials when suitable primer is used
Usage
- Embedment and top coat resin for Sikalastic® RoofPro systems reinforced with Sika Reemat
- Saturating resin for Sikalastic® RoofPro systems reinforced with Sika Fleece
- Typically applied in Sikalastic® RoofPro, Direct, Plaza, Vegetated, and Recover systems for both new construction and refurbishment
Advantages
- Proven technology with over 30 year track record
- Single component - no mixing and ready to use
- Fully reinforced with highly conformable Sika Reemat or Sika Fleece
- Moisture triggered chemistry that is rapidly weatherproof after application
- Resistant to ponding water
- Low VOC formula - low Odor
- Highly elastic and crack bridging
- Seamless and fully adhered
- Vapor permeable
- UV resistant and non-yellowing
- Abrasion and chemical resistant
- Adheres to most common construction materials when suitable primer is used
Packaging
5 gal. (19 L) pail
Colour
White, Standard Gray, Pearl Gray, Steel Gray, Mushroom, Copper Green; Custom Colors Available
Product Details
ENVIRONMENTAL INFORMATION
Environmental Product Declaration (EPD) - Cradle-to-Grave
APPROVALS / STANDARDS
- FM Approval Standard 4470 for Class 1 Roof Covers
- UL 790 Class A
- Miami-Dade
- ASTM D 6083
- Florida Building Code
Chemical Base
Single component, moisture triggered aliphatic Polyurethane
Shelf Life
15 months
Storage Conditions
Store dry between 35 °F and 77 °F (2–25 °C). Condition material to 50–77 °F (10–25 °C) before using for ease of application
Density
11.9 lb./gal. (1.4 kg/cm3)
Solid content by volume
89 % | (ASTM D-2697) |
Volatile organic compound (VOC) content
38 g/l | (ASTM D-2369-81) |
Resistance to Static Puncture
Refer to Sikalastic®-641 Lo-VOC System Data Sheet | (ASTM D-751)) |
Tensile Strength
Refer to Sikalastic®-641 Lo-VOC System Data Sheet | (ASTM D-751) |
Tear Strength
Refer to Sikalastic®-641 Lo-VOC System Data Sheet | (ASTM D-751) |
Solar Reflectance
86.8 % | (ASTM C-1549) (White) |
Thermal Emittance
0.90 | (ASTM C-1371) (White) |
Solar Reflectance Index
108 | (ASTM E-1980) (White) |
Service Temperature
-22–176 °F (-30–80 °C) intermittent
Chemical Resistance
Strong resistance to a wide range of reagents, including paraffin, gasoline, fuel, oil, white spirit, acid rain, detergents and moderate solutions of acids and alkalis. Some low molecular weight alcohols can soften the material. Contact Technical Service for specific recommendations.
External Fire Performance
Class A | (ASTM E 108) |
Application
Ambient Air Temperature
41 °F (5 °C) min. / 95 °F (35 °C) max.
Relative Air Humidity
85 % R.H. max.
Dew Point
Beware of condensation.
The substrate and uncured coating must be ≥ 5 °F (3 °C) above dew point.
Substrate Temperature
41 °F (5 °C) min. / 140°F (60°C) max.
Substrate Moisture Content
≤ 4 % moisture content Test method: Sika®-Tramex meter
No rising moisture according to ASTM (Polyethylene-sheet)
Pot Life
Sikalastic®-641 Lo-VOC is designed for fast curing. High temperatures combined with high air humidity will increase the curing process. Thus, material inopened containers should be applied immediately. In opened containers, the material will form a film after 1–2 hours approx. ( at 75 °F (24 °C) and 50 % R.H.)
Waiting / Recoat Times
Ambient conditions | Minimum waiting time overcoating |
+40 °F / 50 % r.h. | 18 hours |
+50 °F / 50 % r.h. | 8 hours |
+70 °F / 50 % r.h. | 6 hours |
*After 7 days the surface must be cleaned and primed with Sika® Concrete Primer Lo-VOC or Sika® Reactivation Primer before continuing.
Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Applied Product Ready for Use
Ambient conditions | Rain resistant | Touch dry | Full cure |
+40 °F / 50 % r.h. | 1 hour | 12 hours | 24 hours |
+50 °F / 50 % r.h. | 1 hour | 6 hours | 18–24 hours |
+70 °F / 50 % r.h. | 1 hour | 4 hours | 12–18 hours |
Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Coverage
Sika Reemat | Sika Fleece |
80 sf/gal - 20 mils wet film thickness | 24 sf/gal - 66 mils wet film thickness |
69 sf/gal - 23 mils wet film thickness | 32 sf/gal - 50 mils wet film thickness |
53 sf/gal - 30 mils wet film thickness | 35 sf/gal - 45 mils wet film thickness |
32 sf/gal - 50 mils wet film thickness | 53 sf/gal - 30 mils wet film thickness |
NOTE: Coverage rates provided are optimal and are not guaranteed - coverage rates will vary depending on temperature, surface roughness and porosity, aggregate selection and embedment, and application technique. (Refer to Sikalastic® 641 Lo-VOC System Data Sheet)
SUBSTRATE PREPARATION
All substrate surfaces shall be clean, dry and sound. Acceptable substrates include: sound concrete and cementitious screed, metals, wood, modified bitumen, mineralized felt, EPDM, hypalon, TPO, sprayed polyurethane foam, brick and stone, slate and tile, and existing liquid applied membranes. Reference separate System Data Sheet for specific surface preparation requirements.
Primer
Apply primer of a type suitable for the substrate. Allow primer to cure completely before applying Sikalastic®-641 Lo-VOC resin. Reference separate System Data Sheet for specific primer recommendations.
MIXING
No mixing necessary
APPLICATION
Sika Reemat - Base Resin
Apply Sikalastic®-641 Lo-VOC resin to the primed substrate surface by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush at the specified application rate to achieve a uniform and consistent wet mil thickness (reference separate System Data Sheet). Material can also be squeegee or spray applied, in which case it should also be backrolled. Apply Sika Reemat into the wet embedment resin and roll the scrim to achieve full saturation and embedment. Reemat shall be torn/cut to conform to substrate transitions and flashing conditions, with a typical 2” (50.8 mm) reinforcement overlap. Resin shall saturate the Reemat from below. Apply additional Sikalastic®-641 Lo-VOC resin as required to ensure full scrim embedment. Allow to cure completely before applying subsequent resin layers.
Sika Reemat - Intermediate and Top Resin
Apply Sikalastic®-641 Lo-VOC resin to the cured Sikalastic®/Reemat base layer by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush at the specified application rate to achieve a uniform and consistent wet mil thickness (reference separate System Data Sheet). Material can also be squeegee or spray applied, in which case it should also be backrolled. Allow to cure completely before applying any subsequent resin layer, if specified.
Sika Fleece
Apply Sikalastic®-641 Lo-VOC resin to the primed substrate surface by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush to achieve a uniform and consistent thickness, applying approximately 2/3 of the resin required to achieve the specified application rate (reference separate System Data Sheet). Apply Sika Fleece into the wet embedment resin and roll the fleece to achieve partial saturation and full embedment. Fleece shall be cut to conform to substrate transitions and flashing conditions, with typical 3” (76.2 mm) side and 6” (152.4 mm) end reinforcement overlaps. Resin shall saturate the Fleece from below. Apply remaining 1/3 of the specified resin quantity to to ensure full fleece saturation and an even resin application.
CLEANING OF TOOLS
Clean all tools and application equipment with appropriate solvent immediately after use. Hardened and/or cured material can only be removed mechanically.