What is Selleys Storm Sealant, and where should you use it?

Selleys STORM Sealant delivers a waterproof seal on any material, wet or dry, indoors or outdoors — and it can be applied in the rain to stop a leak on the spot. That is the entire reason the product exists. Most sealants need a clean, dry substrate and a settled forecast; Storm Sealant is built for the moment when neither is available and water is coming through the ceiling.

It is designed for urgent roof and gutter leak repairs during and after storms, with good adhesion on most surfaces, a flexible long-lasting seal, and UV and weather resistance. It includes Sil-X™ technology for sealing.

The thing to be clear about before you use it: an emergency seal is not automatically a permanent one. The manufacturer notes it may have limited performance under pressure or in continuous immersion, and that full paint cover is needed for durability. Treat the bead as the repair that buys you time, and the paint coat as the step that makes it last.

Published test data

Selleys publishes a VOC Content Test Certificate for Storm Sealant rather than a full technical data sheet, so figures such as skin time, cure rate and joint movement capability are not available for this product. What is published:

Property	Result
VOC content	32 grams per litre as VOC content per material
GBCA limit for general purpose adhesives and sealants	50 grams per litre
Meets GBCA VOC content requirement	Yes
Test methods	ASTM D3960 and ASTM D2369
Tested	November 2022, by Foray Laboratories (NATA accreditation 1231)
Certificate validity	Issued 23/11/2022, expiry 23/11/2027

The certificate references Green Star Design & As Built V1.3-13.1.1B and Green Star Interiors V1.3-12.1.1B. On a project with a green building specification, that 32 g/L result against a 50 g/L limit is the number the specifier will want.

Separate safety data sheets and technical data sheets are published for the black and grey product and for the clear product.

What "can be applied in the rain" actually means

Applying a sealant to a wet surface in active rain is unusual, and it changes how you work rather than removing the need to work carefully. The directions still start with cleaning the surface as much as possible — wet surfaces are acceptable, but loose debris, moss and flaking material are not. Anything the sealant bonds to had better be attached to the roof.

The application instruction is to apply the sealant liberally over the leak or crack, which is a different technique from a neat structural bead. In an emergency repair the priority is covering the defect completely and pressing material into the penetration, not producing a tidy line.

Where to use it

• Urgent roof and gutter leak repairs, including during storms
• Outdoor and indoor applications
• Wet or dry surfaces
• Most surfaces, where the product is stated to have good adhesion

How to apply it

1. Clean the surface as much as possible. Wet surfaces are still acceptable.
2. Apply the sealant liberally over the leak or crack.
3. Tool it to finish, pressing it into the joint or penetration where you can. Working the material into the defect is what makes the seal, rather than laying it across the top.
4. Once the sealant cures, apply two coats of water-based paint over the top to improve durability.

Painting over it

Storm Sealant is paintable with two coats of water-based paint. If the paint does not wet out the sealant surface properly, lightly sand the sealant before painting. Full paint cover is described as necessary for durability — so unlike most sealants, painting here is part of the repair rather than an optional finish.

Limitations to observe

• May have limited performance under pressure or in continuous immersion. A joint holding back standing water, or one under hydrostatic pressure, is outside what this product is stated to do.
• Full paint cover is needed for durability. An unpainted bead is not the finished job.

Because no full technical data sheet is published for Storm Sealant, there are no stated figures for joint movement capability, service temperature, cure rate or substrate exclusions. If your job depends on a specific movement class or a potable water approval — sealing a gutter that feeds a rainwater tank, for example — use a product that publishes that data. Roof & Gutter Silicone publishes both.

Hazard classification

Classified as hazardous under Safe Work Australia GHS 7, with the signal word Warning. The data below comes from the Australian safety data sheet covering the black, grey and white 290mL cartridges; as the page above notes, Selleys publishes separate documents for the clear product.

• Skin sensitisation — Category 1. H317: may cause an allergic skin reaction.
• Eye irritation — Category 2A. H319: causes serious eye irritation.

It is not classified as Dangerous Goods under the Australian Code for the Transport of Dangerous Goods by Road & Rail, or under New Zealand NZS5433, and its Poison Schedule is not applicable.

What is in it

Chemical entity	CAS number	Proportion (w/w)
Naphtha, petroleum, hydrodesulfurized heavy	64742-82-1	1–10%
Trimethoxyvinylsilane	2768-02-7	1–10%
Benzotriazole derivative	104810-48-2	<1%
1,2-Ethanediamine, N-[3-(trimethoxysilyl)propyl]-	1760-24-3	<1%
Hydroxyphenylbenzotriazole derivative	104810-47-1	<1%
Ingredients determined to be non-hazardous or below reporting limits	—	Balance

The composition is stated to be the same across all the colour variants covered by that data sheet. Reading down it, the formulation lines up with what the page above says the product does. The trimethoxyvinylsilane at 1–10% is a silane cure and coupling chemistry, which is the kind of component that lets a sealant grip a surface that is wet. The two benzotriazole derivatives are the class used as ultraviolet absorbers, which is consistent with the UV and weather resistance claim. And the petroleum naphtha is a solvent carrier. All of that is inference from the chemical classes rather than statements on the data sheet, so read it as explanation, not as sourcing.

The solvent content is worth a moment because of how modest it is. Naphtha at 1–10% is not enough to make this a flammable liquid — there is no flammability classification here at all, and the product is undeclared for transport. Contrast Selleys Sealant Remover, which is more than 60% of the same family of naphtha and is consequently a Class 3 dangerous good with an aspiration hazard. Same chemical family, very different quantity, very different handling.

What does need attention is the skin classification, and the way this product is used makes it worse than the category alone suggests. Category 1 sensitisation is the immune system learning to react: generally permanent once acquired, triggered thereafter by much smaller exposures than the one that caused it, and built up by repeated ordinary contact rather than one accident. Now read the method on this page — apply liberally over the leak, tool it, press it into the penetration. That is deliberately more hand contact than a neat structural bead, done in the rain, on a roof, usually in a hurry, and usually without gloves because nobody puts gloves on for an emergency. The data sheet's own note that effects may be delayed is the tell: a reaction that shows up the next morning is an allergic response, not simple irritation.

Wear gloves and eye protection even for the emergency. Eye irritation at Category 2A is reversible, but working overhead under a gutter, in the wet, with a cartridge above your head, is the geometry that puts sealant in an eye.

Protection

• Gloves and protective clothing, including eye and face protection (P280) — specified for handling.
• Avoid breathing dust, fume, gas, mist, vapours or spray (P261).
• Wash hands, face and all exposed skin thoroughly after handling, and before eating, drinking, smoking or using the toilet (P264).

First aid

Exposure	What to do
Skin	Wash immediately with plenty of soap and water (P302+P352). Effects may be delayed, so keep an eye on the area afterwards and get medical advice if a rash, redness or itching develops later.
Eyes	Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do, then keep rinsing (P305+P351+P338). If eye irritation persists, seek medical advice.

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 Storm Sealant

Can I really apply it while it is raining?

Yes. It delivers a waterproof seal on any material, wet or dry, and can be applied in the rain to stop leaks in an instant.

Does the surface need to be dry?

No. Wet surfaces are acceptable. Clean the surface as much as you can first, so the sealant is bonding to sound material rather than loose debris.

Do I have to paint over it?

For durability, yes. Full paint cover is needed, and the instruction is two coats of water-based paint once the sealant has cured.

What if the paint will not stick to the bead?

If the paint does not wet out the sealant surface properly, lightly sand the sealant before painting.

Can I use it on a joint that is permanently under water?

No. It may have limited performance under pressure or in continuous immersion.

Is it suitable for indoor use?

Yes — it is stated for both outdoors and indoors.

Will it survive sun exposure?

It is described as UV and weather resistant, with a flexible, long-lasting seal.

What colours does it come in?

Selleys publishes separate documentation for black and grey, and for clear.

Does it meet green building VOC requirements?

Yes. Its tested VOC content is 32 grams per litre, against a Green Building Council of Australia limit of 50 grams per litre for general purpose adhesives and sealants.

How long does it take to cure?

No cure rate is published for this product. Apply the paint coats once the sealant has cured.

How much joint movement will it take?

No joint movement figure is published for Storm Sealant. For a joint that has to accommodate measured movement, choose a sealant with a stated movement capability from the roofing silicone range.

What should I use for a permanent repair once the weather clears?

For a planned roof or gutter job, Roof & Gutter Silicone publishes full performance data including movement capability, service temperature and drinking water testing.