What is Selleys No More Gaps Bricks & Mortar, and where should you use it?

Selleys No More Gaps Bricks & Mortar is a textured, ready to use, weather resistant gap filler made to look like mortar. It comes in a range of colours to match existing mortar, and its mortar-like texture is what allows a repaired crack in brickwork to disappear rather than read as a smooth stripe across a rough wall.

The point to be clear on before you buy: this is a repair filler, not a mortar. The manufacturer's stated limitation is that it is not for replacing mortar in construction, and not for moving cracks. It fills and disguises unsightly cracks and gaps in existing brickwork; it does not bed bricks and it is not a structural product.

Technical specification

Property	Typical result
Technology	Water-based
Appearance	Lightly textured paste
Slump resistance	No slump in gaps up to 20mm
Application temperature	>5°C
Tooling time	30 minutes (depending on weather conditions)
Skin time	30 minutes (depending on weather conditions)
Tack-free time	60 minutes (depending on weather conditions)
Hardening	Hardens in 24 hours, depending on weather
Packaging	440 g cartridges
Colours	Off White, Terracotta, Sandstone, Medium Grey, Charcoal

Indicative data only, not intended for the preparation of specifications. Timings marked as weather-dependent will stretch in cold or damp conditions.

What the key numbers mean in practice

No slump in gaps up to 20mm is the number that makes this product usable on a wall. Slump is what happens when a filler sags out of a vertical joint under its own weight before it skins. A 20mm perp joint in brickwork is a real gap, and the product holding its shape in that gap is why you can fill it in one pass instead of building it up in thin layers.

Tooling time and skin time are both 30 minutes, which is generous compared to fast-skinning interior fillers and gives you time to press the product properly into a rough, irregular crack. It is worth using that time — the finish on brickwork depends on working the paste into the texture of the surrounding mortar, not just filling the void.

Hardening takes 24 hours, depending on weather, and for larger cracks and holes Selleys says two applications may be necessary, with the first allowed to dry before the second goes on. So a deep repair is a two-day job, not an afternoon one.

The weather caveat runs through all of it. Until the product is firmly skinned, protect the repair from rain. Rain on an unskinned water-based filler will wash it out of the joint.

Where to use it

The product is suitable for materials such as brick, mortar or concrete, cement render and fibre cement sheeting. Typical uses are:

• Walls
• Pathways
• Tile roof ridge capping

The features Selleys lists for it are a mortar-like texture, more flexible than mortar, weather resistant, UV resistant, mould resistant, water clean up, sandable, paintable and low shrink. The product page adds that it is suitable for indoor and outdoor use.

How to apply it

Surface preparation first: the surface must be clean and free from loose material, grease and flaking or powdery paint. For best results, slightly dampen the surface before application.

1. Ensure the surface is clean and free from loose material, grease and flaking or powdery paint.
2. Cut the nozzle at a 45° angle, cut the cartridge tip, fit the nozzle and insert the cartridge into a caulking gun.
3. Apply with the caulking gun, pushing the product into the gap or joint. Press it into cracks and holes using a spatula or a wet gloved finger.
4. Clean away excess from surfaces immediately using a damp cloth.
5. For larger cracks and holes, apply twice. Allow the first application to dry before applying the second. The product hardens in 24 hours, depending on weather.
6. Protect the repair from rain until it is firmly skinned.

For fine cracks — in cement render, for example — rub the product into the crack rather than gunning it, or use Selleys No More Cracks Exterior & Brick Render instead. If you are painting over the repair, apply an undercoat before the top coat for best results.

Limitations — where it should not be used

• Not for areas of frequent water immersion. The product page puts the same point as not recommended for areas in permanent water immersion.
• Not for replacing mortar in construction, or for moving cracks. A crack that is still moving will reopen through the filler; the underlying movement has to be dealt with first.
• Not suitable as a structural adhesive, per the product page.
• Do not apply or store below 5°C.
• Avoid application in very wet or damp conditions before curing, and protect from rain until firmly skinned.

Clean up and storage

Uncured product may be removed with water — clean excess off the face of the brickwork immediately with a damp cloth, because brick is porous and cured filler smeared across it is much harder to deal with. Cured product can be removed by sanding and scraping.

Do not apply or store below 5°C, and store in a cool, dry place out of direct sunlight.

Hazard classification

Classified as hazardous under Safe Work Australia GHS 7, with the signal word Warning.

• Skin sensitisation — Category 1. H317: may cause an allergic skin reaction.

Not classified as Dangerous Goods by the criteria of the Australian Code for the Transport of Dangerous Goods by Road & Rail or of New Zealand NZS 5433, so no dangerous goods class applies.

What is in it

Chemical entity	CAS number	Proportion (w/w)
Bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate	41556-26-7	<1%
Poly[oxy(methyl-1,2-ethanediyl)], α-(methylphenyl)-ω-hydroxy-	9064-13-5	<1%
1,2-Benzisothiazol-3(2H)-one (BIT)	2634-33-5	<0.05%
5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT)	26172-55-4	<0.05%
2-Methyl-2H-isothiazol-3-one (MIT)	2682-20-4	<0.05%
2-Octyl-2H-isothiazol-3-one (OIT)	26530-20-1	<0.05%
Non-hazardous or below reporting limits	—	Balance

The first entry in that table is almost certainly the UV resistance this page claims. Bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate belongs to the hindered amine light stabiliser family — the additives used to stop a polymer chalking and breaking down under sunlight. The safety data sheet does not say what each ingredient is for, so read that as chemical reasoning rather than a sourced statement; but it is what a UV-resistant exterior filler would be expected to contain, and it is present at a level consistent with a stabiliser rather than a filler component.

The four isothiazolinones are the preservative package, and they are the likely reason for the classification. Four of them at under 0.05% each is a broader package than most of the No More Gaps range carries — which is what a product expected to sit on damp masonry outdoors, and to claim mould resistance, needs. Isothiazolinones are a well-recognised class of skin sensitisers. Again the sheet does not attribute the classification to a single ingredient, so treat that as the likely explanation rather than the sourced one.

Sensitisation is not irritation. Irritation is a local reaction that settles once contact stops. Sensitisation is the immune system learning to react to the material: once acquired it is generally permanent, it can afterwards be triggered by exposures far smaller than the one that caused it, and it tends to worsen with each contact rather than fade. It develops from repeated ordinary contact rather than one big exposure, and the safety data sheet notes that effects may be delayed.

The directions above tell you to press the product into cracks and holes with a spatula or a wet gloved finger. On brickwork that instruction is doing more work than it does indoors: you are pushing filler into a rough, irregular, abrasive surface, working it into the texture of the surrounding mortar, and you have a generous thirty minutes of tooling time in which to do it. That is a long, hands-on contact with wet product on a surface that wears gloves through. Check them, and change them when they go.

Protection

• Gloves — nitrile rubber is suitable for intermittent contact. Selleys notes that glove construction and local conditions vary, so the final assessment is the user's.
• Eye protection — safety glasses.
• Overalls and safety shoes where the job warrants them.
• Wash hands before smoking, eating, drinking or using the toilet, and wash contaminated clothing and protective equipment before storing or reusing it.

First aid

Exposure	What to do
Skin or hair	Effects may be delayed. Remove contaminated clothing and flush the skin and hair with running water. If swelling, redness, blistering or irritation develops, seek medical assistance — it may be an allergic reaction rather than simple irritation.
Eyes	Wash out immediately with water. In any case of eye contamination it is a sensible precaution to get medical advice.
Inhalation	Move the person away from the exposure without putting yourself at risk. Loosen tight clothing, let them rest comfortably and keep them warm until fully recovered. Seek medical advice if effects persist.
Swallowed	Rinse the mouth with water. Do not induce vomiting. Give a glass of water to drink. Give nothing by mouth to an unconscious person. If vomiting occurs, give more water and 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 No More Gaps Bricks & Mortar

Can I use it to lay bricks or repoint a whole wall?

No. It is not for replacing mortar in construction. It is a filler for repairing cracks and gaps in existing brickwork.

What colours does it come in?

Off White, Terracotta, Sandstone, Medium Grey and Charcoal, all in 440 g cartridges. The idea is to match your existing mortar rather than paint the repair afterwards.

How big a gap will it fill without sagging?

It shows no slump in gaps up to 20mm. For larger cracks and holes, two applications may be necessary, letting the first dry before the second.

How long until it hardens?

It hardens in 24 hours, depending on weather. Skin time is around 30 minutes and tack-free time around 60 minutes, both weather dependent.

What happens if it rains?

Protect the repair from rain until it is firmly skinned. It is a water-based product and rain before skinning will damage the fill.

Can I paint over it?

Yes, it is paintable. Apply an undercoat before the top coat for best results.

Can I sand it?

Yes, it is sandable, and sanding and scraping is also how cured product is removed.

Will it work on a crack that is still moving?

No. It is not for moving cracks. Filling a live crack only postpones the reappearance of the crack.

What about very fine cracks in render?

Rub the product into the crack rather than trying to gun it in, or use Selleys No More Cracks Exterior & Brick Render.

Can I use it on a pathway or roof capping?

Yes — walls, pathways and tile roof ridge capping are the uses Selleys lists, on brick, mortar or concrete, cement render and fibre cement sheeting.

Is it waterproof?

It is weather resistant, but it is not for areas of frequent water immersion.

How cold is too cold?

Do not apply or store below 5°C.

For gaps around exterior weatherboards, eaves, windows and doors rather than brickwork, see No More Gaps Exterior. The rest of the range is under gap fillers.