What is Selleys No More Cracks Large Cracks & Holes, and where should you use it?

Selleys No More Cracks Large Cracks & Holes is a ready to use, water based acrylic filler for repairing large cracks and holes on interior and exterior surfaces. It has superior adhesion to plaster, mortar, concrete, timber and primed metal, it sands easily, and it has minimal shrinkage — which is what allows a big repair to be done without coming back to top it up.

The thing to plan around is depth. This filler is sold for large repairs, but "large" refers to the area and the volume, not to how thick a single application can be. Selleys is explicit: for deeper jobs, apply in 6 mm layers, letting each layer dry before the next. A deep hole is a sequence of layers, not one heroic fill.

Technical specification

Property	Typical result
Technology	Water based acrylic
Appearance	Smooth paste, light grey
Sand / paint time — less than 2 mm	2–3 hours
Sand / paint time — up to 6 mm	24 hours
Adhesion	Plaster, mortar, concrete, timber and primed metal
Packaging	230 g tub, 450 g tub, 1 kg tub, 230 g tottle
Minimum temperature	5°C

These are indicative data from the product's technical data sheet only, and are not intended for the preparation of specifications.

What the drying times mean in practice

The two published figures are the most important numbers on this page, and the gap between them is the part to absorb. A fill of less than 2 mm is ready in 2–3 hours. A fill of up to 6 mm takes 24 hours. Tripling the depth multiplies the wait by roughly ten.

That is how water based fillers behave. Drying is water leaving the material through the exposed surface, and the deeper the fill, the further the water has to travel and the more of it there is. A thick fill also skins over first, which slows everything underneath and produces the classic failure: a repair that feels hard, sands nicely, then sinks or cracks days later as the core finally dries.

The layering rule exists to prevent exactly that. Working in 6 mm layers means each layer dries as a shallow fill. It also means a genuinely deep hole is a multi-day job, and it is better to know that at the start than to discover it after painting.

One more instruction attaches to the last layer: overfill the final layer only slightly. Minimal shrinkage means you do not need much excess, and every millimetre of excess is material you have to sand off by hand.

Where to use it

It can be used on multiple surfaces, inside or outside, with superior adhesion to:

• Plaster
• Mortar
• Concrete
• Timber
• Primed metal

The product page also lists brick and stone among the surfaces it suits. Note that the metal is primed metal, not bare.

The choice of pack size follows the job: a 230 g tub or tottle for a handful of repairs, and the 450 g or 1 kg tubs when you are filling a wall's worth of damage. For fine cracks, chips and shallow imperfections on interior surfaces, No More Cracks Small Cracks & Dents is the lighter-duty product; the full range sits on the wall filler page, and Selleys has a walkthrough on how to fill cracks and dents in walls.

How to apply it

1. Make sure the surface is clean and dry, with no loose or powdery material. On a large repair this is the step that decides the outcome — a big fill bonded to crumbling material takes that material with it when it fails.
2. Prime exterior surfaces before filling. Selleys recommends this for exterior work.
3. Use a filling blade or scraper to press the filler firmly in, and scrape off the excess to minimise sanding.
4. For deeper jobs, apply in 6 mm layers, allowing each layer to dry before the next.
5. Overfill the final layer only slightly.
6. Allow it to dry — 2–3 hours for less than 2 mm, 24 hours for up to 6 mm, depending on humidity.
7. Sand back with fine sandpaper when dry.
8. Protect exterior applications from rain until they have been painted over, and apply an undercoat before your top coat.

Choosing a pack size

Four options are published: 230 g and 450 g tubs, a 1 kg tub, and a 230 g tottle. The choice is mostly about how the filler is held while you work. A tottle stands up and is easy to work from one-handed on a ladder; a wide tub suits loading a blade repeatedly on a large repair.

Size follows the layering rule too. If you are filling a deep hole in 6 mm layers, you will use more material than the surface area suggests, so a 230 g pack that looks adequate for the visible damage may not cover a deep one.

It is worth remembering the product is a water based acrylic. That is what gives you water clean up and a repair that takes ordinary paint systems, and it is also why every timing figure on this page is sensitive to humidity: the filler dries by losing water to the air around it.

Limitations — where Large Cracks & Holes should not be used

These are the manufacturer's stated limits:

• Do not use below 5°C — and the product page extends this to storage as well: do not store or use below 5°C.
• Not suitable for exterior timber likely to absorb excessive amounts of water. Timber that takes up water swells and moves, and the repair goes with it.
• Where movement occurs, use Selleys No More Gaps. A large crack that is still opening is a movement problem, and filling it rigidly will not stop it.
• Not for permanent water immersion.

The movement limitation deserves a moment's thought on a big repair, because large cracks are more likely than small ones to be structural in origin. If a crack has visibly widened over time, runs diagonally from the corner of an opening, or reappears in the same line after previous repairs, it is moving. Filling it produces a neat wall for a season.

Clean up and storage

Clean up: uncured product can be removed with water. Once cured, it has to be removed by sanding and scraping — so clean tools, hands and any splashes before the filler dries.

Storage: store in a cool, dry place, and not below 5°C. With pack sizes up to 1 kg, most users will be storing a part-used tub, so seal it properly.

Hazard classification

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

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

It is not classified as Dangerous Goods for transport by road, rail, sea or air.

What is in it

Chemical entity	CAS number	Proportion (w/w)
Poly[oxy(methyl-1,2-ethanediyl)], alpha-(methylphenyl)-omega-hydroxy-	9064-13-5	<1%
2-Octyl-2H-isothiazol-3-one (OIT)	26530-20-1	<0.1%
1,2-Benzisothiazol-3(2H)-one (BIT)	2634-33-5	<0.05%
2-Methyl-1,2-benzisothiazol-3(2H)-one (MBIT)	2527-66-4	<0.05%
Ingredients determined to be non-hazardous or below reporting limits	—	Balance

Almost all of this filler is unclassified material — water, fillers and binders. What is listed is present at well under 1%, and three of the four entries are isothiazolinone preservatives, the biocides that keep a water-based paste from spoiling in the tub. That family of preservatives is the one which carries skin-sensitisation classifications across water-based products generally; the SDS does not attribute the classification to a particular ingredient, so neither does this page.

What H317 means in practice is worth spelling out. Sensitisation is not irritation. Irritation is local and reversible. Sensitisation is the immune system learning to react to the material: once acquired it is generally permanent, it is set off afterwards by exposures far smaller than the one that caused it, and it develops through repeated everyday contact rather than through one memorable incident.

This is the large-volume product in the range, sold in tubs for going over a whole wall or a whole exterior. That is the pattern that matters — not one repair, but an afternoon of them, with a hand in the tub and a finger smoothing each fill. Use a filling knife rather than a thumb where you can, wear gloves where you cannot, and wash the residue off rather than letting it dry on your skin.

The label also asks for a suitable respirator alongside gloves and eye protection, and warns against breathing dust. On this product that is about sanding: a large, deep fill produces a lot of dust when it is brought back flush.

Protection

• Gloves — nitrile rubber, suitable for intermittent contact per the SDS, with the user making the final assessment.
• Eye protection — protective clothing including eye/face protection (P280).
• Respiratory protection — a suitable respirator or dust mask when sanding; avoid breathing dust, fume, mist, vapours or spray.
• Ventilation — natural ventilation is adequate under normal use conditions. Eyewash facilities should be to hand in a workplace setting.
• Keep out of reach of children. Take off contaminated clothing and wash it before reuse.

First aid

Exposure	What to do
Eyes	Wash out immediately with water, holding the eyelids open, and keep rinsing. As a sensible precaution, seek medical advice in all cases of eye contamination.
Skin	Effects may be delayed. Remove contaminated clothing and flush the skin and hair with running water, then wash with soap. If swelling, redness, blistering or a rash occurs — including hours later — get medical advice or attention.
Inhalation	Move the person to fresh air, 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 to drink and seek medical advice. Never give anything by mouth to an unconscious person.

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 No More Cracks Large Cracks & Holes

How long does it take to dry?

2–3 hours for a fill less than 2 mm, and 24 hours for a fill up to 6 mm, depending on humidity.

How do I fill a deep hole?

In 6 mm layers, allowing each layer to dry before applying the next. Overfill only the final layer, and only slightly.

What sizes does it come in?

230 g and 450 g tubs, a 1 kg tub, and a 230 g tottle.

What surfaces does it stick to?

It has superior adhesion to plaster, mortar, concrete, timber and primed metal, and the product page also lists brick and stone.

Can I use it outside?

Yes. Prime exterior surfaces before filling, and protect the repair from rain until it has been painted over.

Does it shrink?

It has minimal shrinkage, which is why only the final layer needs slight overfilling.

Can I use it on exterior timber?

Not on exterior timber likely to absorb excessive amounts of water.

Can I use it in a wet area or somewhere submerged?

No. It is not for permanent water immersion.

What if the crack is still moving?

Use Selleys No More Gaps. A rigid filler will crack again along the same line.

What is the minimum temperature?

5°C, for both storage and use.

How do I clean up?

Water, while the product is uncured. Once cured, it comes off by sanding and scraping.

What should I sand it with?

Fine sandpaper, once dry.

Do I need an undercoat?

For best results, yes — apply an undercoat before your top coat of paint.