What is Selleys Spakfilla Coloursmart, and where should you use it?

Selleys Spakfilla Coloursmart is a ready-mixed, lightweight filler with a built-in dry time indicator. It goes on pink and dries off-white, so the filler itself tells you when it is ready to sand and paint rather than leaving you to guess or prod at it.

That indicator is the reason to choose it, and it solves a real problem. Every other filler asks you to judge readiness from a published time plus an adjustment for depth, temperature and humidity — and sanding early is how a good repair gets dragged out of the hole. Coloursmart replaces the estimate with an observation: when the pink has gone, the filler is ready.

Technical specification

Property	Typical result
Appearance	Pink paste, drying off-white
Drying time (2 mm)	2 hours — allow longer if deeper, or in cold or humid conditions
Maximum single application	Holes up to 10 mm deep, in one application
Packaging	180 g / 400 mL tub
Use	Interior and exterior
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 key numbers mean in practice

Two hours at 2 mm is the baseline, with the standard caveats: allow longer if the fill is deeper, or if conditions are cold or humid. But because the colour change is doing the reporting, that figure is a planning number rather than an instruction. You do not need to decide whether today's weather has added an hour — the filler will still be pink if it has.

The 10 mm figure is the more valuable one. Selleys states that minimal shrinkage means only one easy application is needed for holes up to 10 mm deep. That is unusual. Most fillers in this class require deeper repairs to be built up in layers, with a drying wait between each. Coloursmart lets you fill a 10 mm hole in a single pass, which turns a two-stage job into a one-stage job.

No need to overfill follows from the same minimal shrinkage. Smooth it off flush and leave it — a proud fill just becomes sanding, and on a lightweight filler heavy sanding can cut into the surface around the repair.

One important exception to the colour rule: the indicator tells you when to sand and paint with water-based paints. If you are using oil based paint, allow at least 24 hours regardless of what colour the filler has gone. The pink disappearing means the filler is dry enough for water-based systems, not that the 24 hour oil based wait has been satisfied.

Where to use it

Spakfilla Coloursmart is suitable for filling:

• Plaster
• Plasterboard
• Masonry
• Wallboard
• Primed nail heads

It is rated for interior and exterior use. For exterior work, Selleys attaches a specific condition: protect the repair from rain until it is dry and painted over with two coats of paint. That is a more explicit requirement than "protect until painted" and it is worth honouring — an exterior filler repair is only as durable as the paint system covering it.

The other Spakfilla products cover different priorities: Spakfilla Rapid for speed, Spakfilla Heavy Duty for tougher filling work, and the Spakfilla Wall Repair Kit as an all-in-one option. The full range is on the wall filler page.

How to apply it

1. Prepare the surface. It must be clean, dry and free of loose or protruding material — sand it lightly if necessary.
2. Using the spatula provided, press the filler firmly into the hole or crack and smooth it off. There is no need to overfill: it has minimal shrinkage, and one application handles holes up to 10 mm deep.
3. Wait for the colour to change. The filler goes on pink and is ready when it has turned off-white.
4. Sand and paint with water-based paints once it has turned off-white.
5. For oil based paint, allow at least 24 hours before painting.
6. Outside, protect the repair from rain until it is dry and painted over with two coats of paint.

Before any of that, the surface preparation instruction is worth taking seriously: clean, dry, and free of loose or protruding material, sanded lightly if necessary. Protruding material matters as much as loose material on a shallow repair — anything standing proud of the surface holds your spatula off the wall and leaves the fill sitting high.

A note on appearance after painting: some paints may temporarily discolour when applied over the filler, but will revert to the correct colour once dry. If the first coat looks patchy over your repairs, let it dry before deciding anything is wrong.

Reviving a stiff tub

If the filler has stiffened before use, stir it with a spatula. If it is still too dry, add one teaspoon of water and stir again to the consistency you want. Product that has actually hardened should be discarded — there is no reviving that, and trying to work it into a repair gives you a lumpy fill that will not bond properly.

Limitations — where Coloursmart should not be used

These are the manufacturer's stated limits:

• Do not use on plastic, metal, or exterior timber likely to swell or shrink on absorption of water.
• Avoid using below 5°C or in wet conditions.
• Do not nail. Lightweight filler does not hold a fixing.
• Not for load bearing applications, or where surfaces will undergo structural movement.
• Where movement occurs, use Selleys No More Gaps.

The movement limitations are the ones to weigh before you start. A crack caused by a wall settling or a joint flexing is not a filling problem, and a rigid lightweight filler placed in one will crack again along the same line. The colour indicator tells you when the filler is dry; it cannot tell you whether the filler was the right choice.

Clean up and storage

Clean up: use water before the filler sets.

Storage: keep the container closed when not in use, and store it in a cool, dry place. Because the tub is small — 180 g / 400 mL — and the product is water based, an unsealed lid is what turns the rest of it into the hardened material you have to throw away.

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.
• 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 New Zealand NZS5433.

What is in it

Chemical entity	CAS number	Proportion (w/w)
Alcohols, C12–14, ethoxylated, sulphates, sodium salts	68891-38-3	1–10%
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%
Ingredients determined to be non-hazardous or below reporting limits	—	Balance

The colour change tells you when the filler is dry. It tells you nothing about the hazard. Pink and off-white are the same material chemically, and both carry the classifications above — there is no point in the cure at which the wet product stops being a sensitiser. It is worth saying plainly, because an indicator that is designed to signal “ready” can read as a general all-clear.

Of the two classifications, H319 is the immediate one and H317 is the lasting one. Sensitisation is not irritation: irritation is local and reversible, while sensitisation is the immune system learning to react to the material. Once acquired it is generally permanent, it is triggered afterwards by much smaller exposures, and it develops from repeated casual contact — filling and smoothing with a bare finger, room after room, rather than one memorable splash. The one ingredient present at a percentage rather than a trace is a sodium alkyl ether sulfate, the surfactant family used in detergents, which is a chemical class associated with eye irritation; the SDS does not attribute either classification to a particular ingredient, so this page does not present that as the sourced cause.

Two moments on this product deserve gloves. The first is smoothing the fill. The second is the one the page describes as reviving a stiff tub: stirring in a teaspoon of water and working the paste back to a usable consistency puts your hand into the product for longer than any single repair does, and it is easy to do bare-handed at the bench without thinking about it.

Protection

• Eye protection — safety glasses, and particularly when filling or sanding above head height.
• Gloves — nitrile rubber, suitable for intermittent contact per the SDS, with the user making the final assessment.
• Dust mask — when sanding the dried filler.
• Ventilation — adequate general ventilation in the work area; local exhaust where that is not enough, with respiratory protection as a last resort.
• Wash hands before eating, drinking or smoking. Wash contaminated clothing and protective equipment before storing or reusing.

First aid

Exposure	What to do
Eyes	Rinse cautiously with water for several minutes, holding the eyelids open. Remove contact lenses if present and easy to do, then keep rinsing. If eye irritation persists, get medical advice or attention.
Skin	Remove contaminated clothing and wash with plenty of water and soap. If a rash or irritation develops, 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 Spakfilla Coloursmart

How do I know when it is dry?

When the pink has turned off-white. That is the point at which you can sand and paint with water-based paints.

How long does it usually take?

2 hours for a 2 mm application. Allow longer for deeper fills, or in cold or humid conditions.

Does the colour change apply to oil based paint too?

No. For oil based paint, allow at least 24 hours regardless.

How deep a hole can I fill in one go?

Up to 10 mm deep, in one application — it has minimal shrinkage.

Do I need to overfill?

No. Press it in firmly and smooth it off flush.

What size does it come in?

A 180 g / 400 mL tub.

Can I use it outside?

Yes. Protect the repair from rain until it is dry and painted over with two coats of paint.

What surfaces can I use it on?

Plaster, plasterboard, masonry, wallboard and primed nail heads.

Can I use it on plastic or metal?

No. Do not use it on plastic, metal, or exterior timber likely to swell or shrink with water absorption.

Can I nail into it?

No. Do not nail.

My paint looks discoloured over the filler — is something wrong?

Probably not. Some paints may temporarily discolour when applied over the filler and revert to the correct colour once dry.

The tub has gone stiff. Can I use it?

Stir it, and if it is still too dry add one teaspoon of water and stir again. If it has actually hardened, discard it.

What is the minimum temperature?

Avoid using it below 5°C, or in wet conditions.

How do I clean up?

With water, before the filler sets.