What is Selleys Special Putty, and where should you use it?

Selleys Special Putty is a superior linseed oil-based putty for glazing timber frame windows and door panels. It is suitable for face glazing (the putty on the front of the glass), heel seal (the bed behind the glass) and bedding glazing beads (the wooden strip that retains the glass).

The thing to be clear about before you buy is that this is a glazing putty, not a general filler. It is not for filling nail holes or timber splits, and it is not for metal window frames. Its job is holding glass in a timber rebate, and everything about how it is used follows from that. If you are filling timber rather than glazing it, look at the rest of the wood putty range.

What linseed oil putty asks of you

Traditional linseed oil putty is not a modern sealant and does not behave like one. Three things follow from that, and all three are in the manufacturer's own instructions.

First, it skins rather than cures. You apply it, it forms a surface skin, and only then can it be painted. That is why the direction is to allow it to skin before painting rather than to wait a stated number of hours.

Second, it needs paint to survive. The instruction is to paint between 2 and 4 weeks after glazing. Too early and the putty has not skinned enough to take the coating; too late and it has been weathering unprotected. That window is the single most commonly missed step in a putty glazing job.

Third, it is maintained, not installed and forgotten. Selleys asks you to inspect every 6 to 12 months and repair if required. A putty line that is checked annually and patched where it has cracked will outlast one that is left alone until the glass rattles.

Its exceptional keeping qualities refer to the putty in storage — it stays workable in the tin rather than going off quickly — which is why it is practical to keep a container for the annual inspection and touch-up rather than buying fresh each time.

Where to use it

• Glazing timber frame windows and door panels
• Face glazing — the finished putty fillet on the front of the glass
• Heel seal — the bed of putty behind the glass
• Bedding glazing beads — the wooden strip that retains the glass

It is for use with timber frames and glass. That pairing is the whole scope of the product. For general glazing work outside those materials, it is the wrong choice.

How to apply it

1. Ensure rebates are clean, dry and correctly sized. A rebate that is the wrong size cannot be corrected with more putty.
2. Remove the surface skin from the putty and soften it in your hands. Working the putty warm and pliable is what makes it press into the rebate properly instead of tearing.
3. Apply to the rear of the rebate to form the heel seal.
4. Install the glass and fix it with pins. The pins hold the glass; the putty seals it. Do not rely on the putty to hold the glass in place.
5. Apply the front putty and smooth it off.
6. Allow it to skin before painting — then paint between 2 and 4 weeks after glazing.

Putty can be applied by hand or with a putty knife. A few drops of linseed oil on your hands or the knife will make for easier working — the putty stops dragging and releases cleanly from the blade.

Limitations — where Special Putty should not be used

• Not for metal window frames.
• Not for filling nail holes or timber splits.
• Not suitable where structural movement may occur.
• Not recommended with timber stains, oils or clear varnish finishes in exterior applications.
• For glass areas over 1.25m², use bead glazing or an elastomeric sealant instead.

The 1.25m² threshold is a real engineering limit rather than a suggestion. A large pane exerts far more load on the glazing line, and a putty fillet is not built to carry it. Above that size, the glass should be retained by beads or sealed with an elastomeric sealant that can move with it.

The finish restriction matters just as much for exterior windows. Stains, timber oils and clear varnishes are not recommended over putty outdoors — the putty needs the protection a paint film gives it.

Clean up

Clean uncured putty with methylated spirits. Do this while the putty is still soft; once it has skinned and hardened, removal becomes a mechanical job.

Hazard classification

Selleys Special Putty is not classified as hazardous under the criteria of Safe Work Australia GHS 7. It carries no signal word and no hazard statements, and its safety data sheet lists every ingredient as non-hazardous or below reporting limits.

That is a positive statement from the product's own safety data sheet rather than an absence of information, and it is worth stating because most of the specialist fillers and putties beside it are classified — several for skin sensitisation, and the two-pack polyester fillers for reproductive toxicity and organic peroxide hazards. If the job can be done with a traditional linseed oil putty, the hazard profile is far simpler.

Ordinary precautions still apply

• Hands. Not classified as an irritant is not the same as pleasant to work with all day. Wash hands before eating, drinking or smoking.
• Eyes. Rinse with water if any gets in, and get medical advice if irritation persists.
• Keep out of reach of children, and store it sealed so it does not skin over.

If poisoning occurs, contact a doctor or the Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions about Selleys Special Putty

What is it actually for?

Glazing timber frame windows and door panels — face glazing, heel seal and bedding glazing beads.

Can I use it to fill nail holes?

No. It is not for filling nail holes or timber splits.

Can I use it on aluminium or steel window frames?

No. It is not for metal window frames — it is for timber frames and glass.

When should I paint it?

Between 2 and 4 weeks after glazing, once it has skinned.

Do I have to paint it at all?

Painting is part of the specified process. In exterior applications, timber stains, oils and clear varnish finishes are not recommended over the putty.

How big a pane can I glaze with it?

Up to 1.25m². For glass areas over that, use bead glazing or an elastomeric sealant.

The putty is hard to work — what can I do?

Remove the surface skin and soften it in your hands. A few drops of linseed oil on your hands or the putty knife will make it easier to work.

Do the pins matter, or will the putty hold the glass?

The glass is fixed with pins as part of the process. Install the glass into the rear putty and pin it, then apply the front putty.

How often should I check the putty line?

Inspect every 6 to 12 months and repair if required.

Can I use it on a frame that moves?

No. It is not suitable where structural movement may occur.

How do I clean up?

Methylated spirits will remove uncured putty.

Does it keep well once opened?

Yes — exceptional keeping qualities are one of its stated features, which suits a product used for periodic repairs.