Sika Sikafloor-305 W
A water-based, low-VOC two-component polyurethane matt seal coat that protects and finishes resin floors with good UV and yellowing resistance.
What is it?
A two-part, water-based polyurethane matt seal coat pigmented in colour, built on Sika Purform technology and supplied as part of the ComfortFloor range.
Where is it used?
As the top seal over Sika ComfortFloor, Sikafloor MultiFlex polyurethane and Sikafloor MultiDur epoxy systems in hospitals, schools, showrooms, offices and light commercial areas.
Why use it?
It closes the floor with a low-odour, low-VOC film that resists UV yellowing, cleans easily and keeps the finish looking uniform and matt.
How is it applied?
Mix Part A and B 85:15 by weight with 5-10% clean water, stand 10 minutes, then apply one coat by short-pile nylon roller or airless spray at about 0.13 kg/m.
About Sika Sikafloor-305 W
Sikafloor-305 W is the finishing layer that a good resin floor is often judged by. It is a two-component, water-based polyurethane seal coat that goes down over an existing Sika flooring build-up and gives it a uniform coloured matt appearance, a cleanable surface and protection against everyday wear and light. Because the carrier is water rather than solvent, the product is low in odour and low in VOC, which matters a great deal on occupied sites such as hospitals, schools and offices where a solvent seal coat would force long shutdowns or ventilation headaches. It is formulated with Sika Purform polyurethane technology and carries CE marking under both EN 1504-2 (surface protection of concrete) and EN 13813 (synthetic resin screed material).
For engineers and applicators in India, the practical appeal is that Sikafloor-305 W is a system component, not a standalone floor. It is designed to seal three specific Sika families: the ComfortFloor comfort/decorative range, the Sikafloor MultiFlex polyurethane range and the Sikafloor MultiDur epoxy range. That means specification is straightforward once the base system is chosen, and the seal coat’s UV and yellowing resistance protects the colour of the layer beneath it. At roughly 0.13 kg/m per coat it is an economical, thin-film top layer, but it is also an unforgiving one: it will not hide a dirty, uneven or poorly prepared substrate, so the quality of the coat you see is really the quality of the work underneath it.
The technical insight
The performance comes from a waterborne two-component polyurethane chemistry. Part A carries the pigment and the polyol-side resin in water; Part B is the isocyanate-functional hardener. When the two are mixed 85:15 by weight and diluted with 5-10% clean water, the water first acts as a carrier that lets the coating flow and level, then evaporates as the polyurethane cross-links to form a continuous, closed film. That cured film is what delivers the useful properties: a Shore D hardness of about 84 after seven days for scuff and foot-traffic resistance, tensile adhesion above 1.5 N/mm with failure occurring in the concrete rather than the bond line, and a genuinely matt look (gloss below 10 at 60 degrees). Because it is an aliphatic-type PU built on Purform technology, the film holds its colour under UV far better than an aromatic epoxy top coat, which is why it is trusted where daylight or interior lighting would otherwise yellow the surface. The trade-off inherent to any waterborne coat is moisture sensitivity during cure, so relative humidity, dew point and ventilation are not optional details but the mechanism that decides whether the film forms correctly.
Where it is used
- Matt seal coat over Sika ComfortFloor decorative and comfort flooring systems
- Top seal for Sikafloor MultiFlex polyurethane floors
- Top seal for Sikafloor MultiDur epoxy floors
- Healthcare floors, wards, corridors and clinics needing low-odour installation
- Schools, colleges and institutional buildings
- Retail showrooms, malls and display areas where colour stability matters
- Offices, lobbies and public circulation spaces
- Light commercial kitchens and back-of-house areas
Key advantages
- Water-based and low-VOC, so it can be applied in occupied or ventilation-limited spaces
- Low odour compared with solvent-borne seal coats
- Good UV resistance and good yellowing resistance keep the colour stable over time
- Matt, easy-to-clean finish that lowers long-term maintenance
- Strong bond to concrete, with adhesion failing in the substrate rather than the film
- CE marked under EN 1504-2 and EN 13813 for concrete protection and resin screeds
- Tools clean up with water while the product is still wet
- Purpose-matched to Sika ComfortFloor, MultiFlex PU and MultiDur epoxy systems
Limitations & considerations
- A thin seal coat only, not a build layer; it cannot hide uneven, dirty or contaminated substrates
- Application window is narrow at +10 C to +30 C and maximum 75% relative humidity
- Cure is moisture-sensitive; the floor must stay at least 3 C above dew point and be protected from water for at least 24 hours
- Short pot life, from about 80 minutes at +10 C down to roughly 30 minutes at +25 C
- Epoxy substrates must be sanded first to secure adhesion
- Only electric warm-air heaters may be used; gas, oil or paraffin heaters can damage the finish
Selection & best practice
Treat surface preparation and site conditions as the job, not an afterthought. Confirm the substrate is sound (minimum 25 N/mm compressive, 1.5 N/mm tensile), clean, dry and vacuumed, and sand any epoxy base with a 3M Brown Stripper Pad before coating. Stir Part A to a uniform colour, add all of Part B, then mix continuously for about three minutes while adding 5-10% clean water (use the maximum water for the smoothest surface), and let the mix stand 10 minutes before use. Divide the floor into sections that can be finished without stopping, cut in corners and columns by short-pile roller, then lay the coat crosswise at 0.13 kg/m keeping a wet edge throughout for a seamless finish. Watch the clock against pot life in warm weather, keep the floor above dew point, ventilate well, and protect the fresh coat from moisture and condensation for at least 24 hours. For exact colour matching, take material for a given area from the same batch number.
Specifications
| Chemical base | Water-based 2-component polyurethane (Sika Purform) |
| Finish / colour | Coloured, matt (gloss <10 at 60 degrees, <50 at 85 degrees) |
| Mixing ratio | Part A : Part B = 85:15 by weight, plus 5-10% clean water |
| Packaging | 10 kg unit (Part A 8.5 kg + Part B 1.5 kg) |
| Consumption | 0.13 kg/m per coat (diluted with 10% water) |
| Shore D hardness | ~84 after 7 days at +23 C (EN ISO 868) |
| Tensile adhesion | >1.5 N/mm, failure in concrete (EN 1542) |
| Pot life | 80 min at +10 C; 60 min at +20 C/50% r.h.; 30 min at +25 C |
| Application / cure conditions | +10 C to +30 C, max 75% r.h., min 3 C above dew point |
Industry use cases
Healthcare
Seals ward, corridor and clinic floors with a low-odour, low-VOC coat that lets occupied hospital areas be recoated with minimal disruption and cleaned easily.
Education
Finishes classroom, hostel and corridor floors in schools and colleges where a hard-wearing, easy-clean matt surface is needed over holiday shutdowns.
Retail and showrooms
Protects the colour of decorative ComfortFloor systems in shops and display areas thanks to good UV and yellowing resistance under bright lighting.
Commercial offices
Provides a uniform matt seal for lobbies, circulation zones and open-plan offices that keeps maintenance low and appearance consistent.
Light commercial kitchens
Adds a cleanable seal layer over resin floors in back-of-house and food-prep areas where hygiene and easy washdown are priorities.
Frequently asked questions
What exactly is Sikafloor-305 W used for?
How much do I need per square metre?
Is it low odour enough for occupied buildings?
What is the pot life and working window?
Can I apply it over an existing epoxy floor?
How long before the floor can take traffic?
How we position Sika Sikafloor-305 W
Sikafloor-305 W sits at the top of a Sika resin floor as its protective, colour-stable finish, so it is naturally specified alongside the systems it seals: Sikafloor MultiDur epoxy for the hard-wearing base, Sikafloor MultiFlex for crack-bridging polyurethane floors, and the ComfortFloor range for decorative and comfort applications. Where a project instead calls for a Fosroc build, the direct counterpart in our range is Fosroc Nitocote PUW100, a water-dispersed pigmented polyurethane seal that fills a very similar dustproofing and easy-clean role. Contractors comparing brands often weigh Sika’s ComfortFloor system integration against Fosroc’s wider availability on Indian sites. As an authorised distributor and applicator across Delhi NCR and pan-India, Space Arc can supply and apply either family and advise on the right base system, primer and self-levelling layers to pair beneath the seal coat.
Fosroc Nitocote PUW100 — Specify the Fosroc water-dispersed PU seal when the floor build-up is Fosroc-based or when a single-component, pigmented dustproofing seal is preferred for easier site handling.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.