Selleys VBS Rapid

What is Selleys VBS Rapid, and where should you use it?

Selleys Liquid Nails VBS Rapid is a highly cross-linked, pigmented, two-pack epoxy water based vapour barrier system. Its job is to seal concrete floor slabs to reduce the amount of water vapour emanating from the concrete, so that a timber floor laid over the slab is not being fed moisture from underneath for the rest of its life.

It is supplied as a 5 litre kit in two aluminium foil pouches, mixed 1:1 by weight or volume, and the mixed product is mid green. It is normally a one-coat system and it cures fast: floors can typically be walked on, re-coated or adhered to in 2–4 hours.

The single most important number is the performance target it is designed to meet: a moisture vapour transmission rate of less than 15g/m²/24 hours. That is the threshold a slab needs to be under before a timber overlay goes down, and it is why this product exists.

Technical specification

Property	Typical result
Technology	Two part water based epoxy
Colour	Resin: white. Hardener: green. When mixed: green
Density	1.2
Mix ratio	1:1 by weight or volume
Packaging	5L kit, 2 x aluminium foil pouches
Coverage	40m² per coat for engineered flooring; 20m² per coat for solid timber flooring (per pack)
Application temperature	10 – 35°C
Working time	Under 40 – 45 minutes at 25°C
Cure time	Normally walked on, re-coated or adhered to in 2–4 hours
Re-coat time	After curing and before 72 hours
Water vapour barrier permeance	Will achieve an MVT of less than 15g/m²/24 hours
VOC content (ASTM D3960-05)	151 grams per litre

These figures are indicative data only and are not intended for the preparation of specifications.

What the key numbers mean in practice

Coverage differs by a factor of two depending on what you are laying over it. A pack covers approximately 40m² for engineered flooring or 20m² for solid timber floors. Solid timber gets double the film thickness, because it is the more demanding overlay — a thicker barrier is what protects it. Work out which figure applies to your job before ordering, because getting this wrong halves or doubles your material requirement.

Working time is under 40 to 45 minutes at 25°C, and the data sheet is emphatic about it. If the mixed product begins to thicken before it has been applied, it has exceeded its working time and should not be used. That is not a soft warning about finish quality — a thickened epoxy will not form the continuous film the barrier depends on. Mark out your area and have everything ready before you mix.

The 2–4 hour cure lets you finish in a day. When the product is touch dry and able to be walked on, laying of flooring can typically commence on the same day — minimum 2 hours in summer, minimum 4 hours in winter at ambient temperature. Good ventilation accelerates water loss, and available heat sources will accelerate the cure so overlays can be installed earlier.

Re-coat after curing and before 72 hours. If a second coat is needed, that is the window. It is not stated what to do outside it for this product, so plan the second coat into the same working period rather than leaving it a week.

The green pigment is a working tool, not decoration. Selleys calls this controlled opacity: the mid green colour of the mixed product lets you gauge a consistent application rate by eye. The data sheet adds that the product darkens as the water evaporates, and the colour gives a visual indication of varying thickness — shallow areas tend to give a "grin-through" effect where the substrate shows through. If you can see grin-through, that area is too thin.

Where to use it

• Sealing concrete floor slabs to reduce water vapour emanating from the concrete
• On concrete slabs prior to using Selleys Liquid Nails flooring adhesives to lay timber flooring

Surface preparation

All surfaces must be clean, dry and sound, free of voids, loose materials and contaminants — curing compounds, oil, grease, waxes, sealers, previous coatings or adhesives. Complete removal of any contamination must be carried out wherever it is suspected or evident.

• Preparation may be achieved by diamond grinding, shot blasting, sand blasting or captive abrasive blast cleaning. Acid etching is not recommended, because the concrete then has to be neutralised and dried afterwards.
• Diamond grinding is the best preparation, because it removes high spots as well as laitance.
• The surface must be structurally sound and level. Concrete slabs shall be in accordance with AS2870-1996 Residential Footings and Slabs Code, and concrete should be flat and level (refer ASTM F710-98).
• Concrete surfaces shall have a finish equivalent to that obtained when using a steel trowel.
• The product can be applied if the concrete surface is dry and the slab has stabilised. To be stable, new concrete should be cured for at least 28 days.

Checking for dampness before you start

The data sheet gives a simple field test. Securely tape a 1m x 1m square of heavy duty plastic onto the slab and leave it for 24 hours. Any visible dampness or discolouration of the slab under the patch when you lift the plastic is a warning sign.

Two situations need more than a coating:

• If the slab is below grade and there is a possibility of the water table being high enough to pressurise the concrete, perimeter drains would need to be installed.
• If the slab is still green and high in water-of-placement, allow the excess water to migrate out with good ventilation or a dehumidifier until the surface is dry.

Slabs known to be, or prone to, high moisture levels may require 2 applications.

How to mix and apply it

1. Complete all preparation first. VBS Rapid cures rapidly — have the application area clear and marked out before you begin mixing.
2. Add ALL the green hardener component to the white resin component in a 10L pail. Once blended, the mix is a uniform green.
3. Mix with a Jiffy mixing blade on a slow speed drill, or the stirrer supplied. Use the stirrer to scrape around the sides and the bottom of the resin can so all the resin is properly incorporated. Streaks of green or white demonstrate insufficient mixing. Mix for approximately two minutes.
4. Once thoroughly mixed and streak free, apply by brush, a 5–6mm mohair roller, an applicator to minimise splatter, or a trowel.
5. Cut in around edges, corners and fine cracks with a brush before completing the roll-out.
6. Use the mixed product within 40 minutes. If it begins to thicken before being applied, it has exceeded its working time and should not be used.
7. Check the finish. The surface should be even, glossy and streak free. To be effective as a vapour barrier there must be a continuous film left on the surface. If that is not achieved in one coat, a second coat is required — and if the coating soaks away, gives dull patches, or shows pinholes, apply a second coat once the first has cured.
8. Ventilate well to accelerate water loss. Available heat sources will accelerate the cure and let overlays be installed earlier.
9. Lay flooring once the product is touch dry and can be walked on — typically the same day, minimum 2 hours in summer and 4 hours in winter.

Mixing less than a whole kit: calculate the area to be coated and use the blend sheet on the data sheet to work out the quantity to mix. As a reference point from that sheet, a 20m² area takes 5L of mixed product for solid timber flooring or 2.5L for engineered flooring. The mix ratio remains 1:1 by volume or weight.

Limitations

• In unusual circumstances, two coats may be required on very porous concrete.
• Mixed product that has begun to thicken must not be used.
• Not suitable over damp or contaminated substrates.
• Apply within the stated 10–35°C application temperature range.

Clean up and storage

Clean up with water before the product cures, using damp rags to remove any splatter from walls. Once an epoxy has cured, water is no longer an option — which is why the splatter is worth dealing with as it happens rather than at the end of the job.

Store in a cool dry place out of direct sunlight, with containers sealed when not in use. Warnings, first aid and shipping information are on the product SDS available through the Selleys website.

Hazard classification

VBS Rapid is a two-pack product, and the two packs are classified separately. Both are hazardous under Safe Work Australia GHS 7, but they are not equally hazardous, and the hardener is the one to treat with respect.

Resin (Part A) — signal word Warning.

• Acute toxicity, oral — Category 4. H302: harmful if swallowed.
• Eye damage/irritation — Category 2A. H319: causes serious eye irritation.

Hardener (Part B) — signal word Danger.

• Skin corrosion/irritation — Category 2. H315: causes skin irritation.
• Sensitisation, skin — Category 1. H317: may cause an allergic skin reaction.
• Eye damage/irritation — Category 1. H318: causes serious eye damage.

Both components are Dangerous Goods Class 9 — miscellaneous dangerous goods — under the Australian Code for the Transport of Dangerous Goods by Road & Rail and New Zealand NZS5433, and under the IMDG and IATA codes. Both meet the description of an environmentally hazardous substance, UN 3077 or UN 3082.

What is in it

Resin (Part A)

Chemical entity	CAS number	Proportion (w/w)
2,2-Bis(4'-glycidyloxyphenyl)propane	1675-54-3	30–60%
Neodecanoic acid, oxiranylmethyl ester	26761-45-5	1–10%
Nonylphenol, ethoxylated	127087-87-0	1–10%
Non-hazardous or below reporting limits	—	Balance

Hardener (Part B)

Chemical entity	CAS number	Proportion (w/w)
1,3-Benzenedimethanamine	1477-55-0	1–10%
Triethylenetetramine	112-24-3	1–10%
2,4,6-Tri(dimethylaminomethyl)phenol	90-72-2	1–10%
Non-hazardous or below reporting limits	—	Balance

The difference between the two signal words is worth understanding before you open the pouches. The resin is an epoxy resin that you should not swallow and should keep out of your eyes. The hardener is an amine blend, and amines are the reason epoxy systems have the reputation they do: it is classified for serious eye damage, not eye irritation. Category 1 means the damage is not assumed to reverse. A splash from the hardener pouch is an emergency, and it is a different event from a splash of the resin.

H317 on the hardener is the one that catches people who have used epoxies for years without trouble. Skin sensitisation is not irritation. It is the immune system learning to react to the amine, it is generally permanent once acquired, and thereafter far smaller exposures set it off. It develops from repeated casual contact — a thumb on the pouch seal, wiping a roller, a smear wiped off with a rag — rather than from one big splash. Gloves on a job you have done a hundred times are protecting you against the hundred-and-first.

Once mixed, treat the working batch as carrying the hardener's hazards, not the resin's, until it has cured. The mixed product is only benign after it has set.

The Class 9 listing is an environmental classification, and it has a practical consequence for the clean-up the directions describe. Washing uncured product off rollers and rags with water is right, but the washings carry the same environmentally hazardous material. Collect them and let them cure out rather than sending them to a stormwater drain.

Protection

• Eye protection — a face shield or chemical goggles while decanting and mixing. Safety glasses are not enough against a Category 1 eye hazard.
• Gloves — nitrile rubber is indicated for intermittent contact; make your own final assessment for your conditions and glove construction.
• Clothing — overalls, apron and rubber boots for mixing and pouring. Wash contaminated clothing and equipment before reuse.
• Ventilation — use with adequate ventilation. This also suits the cure, since the product loses water as it sets.
• Wash hands before eating, drinking, smoking or using the toilet.

First aid

Exposure	What to do
Eyes — hardener	Irrigate immediately with copious water for 15 minutes, holding the eyelids open. Remove contaminated clothing and wash the skin. Seek medical assistance urgently and transport to hospital: the material can cause corneal burns.
Eyes — resin	Hold the eyelids apart and flush continuously with running water until told to stop by the Poisons Information Centre or a doctor, or for at least 15 minutes, then go to a doctor or hospital.
Skin	Remove contaminated clothing and flush skin and hair with running water. For gross contamination, drench with water, remove clothing and keep flushing with plenty of water and soap. Cover any burn with a clean dry dressing; do NOT break blisters. Seek medical assistance if swelling, redness, blistering or irritation occurs. With the hardener the effects may be delayed, and the material can be absorbed through the skin.
Inhalation	Move the person to fresh air without becoming a casualty yourself. Loosen tight clothing, let them sit or lie however is most comfortable, and keep them warm and at rest until recovered. Seek medical advice if effects persist.
Swallowed	Rinse the mouth with water. Do NOT induce vomiting. Give a glass of water. Never give anything by mouth to an unconscious person. Call the Poisons Information Centre or a doctor immediately.

If poisoning occurs, contact a doctor or the Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand — with the container to hand. Selleys emergency line: 1800 220 770 in Australia, 0800 220 770 in New Zealand.

Common questions about Selleys VBS Rapid

How much area does a kit cover?

Approximately 40m² for engineered flooring, or 20m² for solid timber floors, per 5L pack.

What is the mix ratio?

1:1 by weight or volume — all the green hardener into the white resin.

How do I know it is mixed properly?

The mix should be a uniform green with no streaks. Streaks of green or white mean it is not mixed enough. Mix for around two minutes, scraping the sides and bottom.

How long do I have to apply it?

Under 40 to 45 minutes at 25°C. Use the mixed product within 40 minutes, and discard it if it starts to thicken before application.

When can I lay the floor?

Typically the same day, once the product is touch dry and can be walked on — minimum 2 hours in summer, minimum 4 hours in winter at ambient temperature. The technical figure is 2–4 hours.

How do I know if one coat is enough?

The surface should be even, glossy and streak free, with a continuous film. If the coating soaks away, gives dull patches or shows pinholes — or if you can see grin-through where the coat is thin — apply a second coat once the first has cured.

When can I re-coat?

After curing and before 72 hours.

How do I test the slab for dampness?

Tape a 1m x 1m square of heavy duty plastic to the slab, leave it 24 hours, and look for dampness or discolouration underneath when you remove it.

How old does the concrete need to be?

New concrete should be cured for at least 28 days and the slab must have stabilised, with the surface dry.

Can I acid etch the slab first?

Acid etching is not recommended — the concrete then has to be neutralised and dried. Diamond grinding is the best preparation.

What do I apply it with?

A 5–6mm mohair roller, a brush, an applicator to minimise splatter, or a trowel. Cut in the edges with a brush first.

How do I clean up?

With water, before the product cures.

Do I need a primer over it before levelling compound?

Where a self-levelling compound follows, VP30 Primer is the bridging primer in this system — used undiluted over VBS Rapid. Check the VP30 data sheet for the detail.

What adhesive goes over it?

Selleys Liquid Nails flooring adhesives — see Timberflex and Direct Stick, and the full flooring range.