How To Glue Fibreglass Insect Screen to Canvas

What is the best adhesive for gluing fibreglass insect screening to canvas?

Be realistic about this one before you start: flyscreen mesh is genuinely difficult to glue. The open weave gives an adhesive very little surface area to grip, and the fibre itself is not an easy substrate. Selleys names two options — Selleys All Fix Multi Grip, a solvent-based glue that has some body to it and stays flexible to a degree, or a neutral cure silicone such as Selleys Roof & Gutter Silicone.

The two work in different ways, and which one suits you depends on whether you need a thin flexible join or a thick one that fills the weave.

Why mesh is hard to bond

An adhesive bond needs contact area. A woven flyscreen is mostly holes, so a thin glue line only touches the strands where they cross the canvas — a fraction of the footprint of a solid patch. That is why a product with body works better here than a thin, fast-wicking glue: it can build a layer that surrounds the strands and keys through the weave rather than just wetting the top of them.

That is the case for the silicone option. A neutral cure silicone applied to the canvas, with the mesh pressed into it so the sealant squeezes up through the openings, mechanically locks the mesh in place as well as adhering to it.

Using Roof & Gutter Silicone for this

Selleys Roof & Gutter Silicone is a neutral-cure, 100% silicone sealant. Neutral cure matters here because it does not release acetic acid as it sets. Its published figures:

Property	Typical result
Technology	100% silicone, neutral (moisture) cure
Skin time	5–10 minutes
Tooling time	5 minutes
Tack-free time	30 minutes
Cure rate	2 mm / 24 hours
Joint movement	±25%
Elongation at break	330% (ASTM D412)
Application temperature	+5 °C to +30 °C
Service temperature	−60 °C to +150 °C

Figures are indicative and based on current product material data and test conditions.

The 5-minute tooling window is the one to plan around. You have about five minutes from laying the bead to pressing the mesh in and working it down; after the skin forms at 5–10 minutes, further tooling tears the surface instead of smoothing it. Lay out and cut everything before you open the cartridge.

The 2 mm per 24 hours cure rate means a thick bed of silicone under a mesh strip is not fully cured overnight. Leave it undisturbed rather than testing it.

Substrate cautions — read these first

• Pre-test. Canvas is not among the substrates listed on the Roof & Gutter Silicone TDS, and Selleys' standing recommendation is to apply a sample to the intended area first to confirm appearance, finish and performance. Do that on an offcut.
• Plasticisers. The TDS says to avoid contact with materials containing high levels of plasticisers, such as rubber and bituminous substrates — components in them can migrate into the sealant and cause staining or reduced performance. Many flyscreen meshes are PVC-coated; PVC itself is a listed substrate, but a heavily plasticised coating is a reason to test rather than assume.
• Not for polyethylene, polypropylene or PTFE. If the mesh is a polyolefin rather than fibreglass, silicone will not hold it.
• Not paintable, and it needs atmospheric moisture to cure — in very dry conditions cure slows.
• Apply between +5 °C and +30 °C, and not when the ambient or substrate temperature is below +5 °C or above +40 °C.

The All Fix Multi Grip option

All Fix Multi Grip is the solvent-based general-purpose glue Selleys names for this job. It has enough body to sit in the weave and remains flexible to some extent, which suits a screen that has to fold or flex with the canvas. Selleys does not publish a technical data sheet for All Fix Multi Grip, so we cannot give you open times, coverage or cure figures for it here — work to the directions on the pack, and give the solvent time to escape from a bond made through an open mesh. Current all-purpose glues are listed on the all-purpose glues page.

How to do it

1. Cut the mesh oversize and lay the canvas flat and taut, with something behind it that the adhesive cannot stick to.
2. Clean and dry both surfaces. Old canvas carries proofing, wax and grime, and none of it helps.
3. Test on an offcut of the same canvas and mesh. Give it a full day, then try to peel it.
4. If you are using silicone: cut the cartridge tip, fit the nozzle, trim to a bead width slightly wider than the mesh edge, and lay a continuous bead on the canvas.
5. Press the mesh into the wet bead within five minutes so the sealant comes up through the openings, then tool it flat with a clean spatula dipped in soapy water before the skin forms.
6. Leave it undisturbed. At 2 mm per 24 hours, allow at least a day for a thin bed and longer for a thick one.

Safety: pressing mesh into wet sealant is a hand-contact job

Roof & Gutter Silicone is classified Warning — H319 (causes serious eye irritation) and H317 (may cause an allergic skin reaction).

Selleys Sealant Remover, named in the clean-up answer above, is classified Danger, Poison Schedule S5, with H304 (may be fatal if swallowed and enters airways), H226 (flammable liquid and vapour), H336 (may cause drowsiness or dizziness) and H315 (causes skin irritation). It is more than 60% petroleum naphtha. No safety data is reproduced here for All Fix Multi Grip; read the classification on the pack before you use it.

What follows from that for this job

H317 is the classification the method above walks straight into. The technique is to press mesh into a wet bead so the sealant squeezes up through the weave, then tool it flat. That is deliberate, sustained contact with uncured silicone across the whole length of the repair — and open mesh abrades a glove or a fingertip as you work it down. Skin sensitisation is not irritation that passes. It is the immune system learning to react, generally permanent once acquired, and thereafter set off by exposures far smaller than the one that caused it. It is built from repeated casual contact, which is exactly what this job is. Use the spatula the method already specifies, keep nitrile gloves on for the full run, and change them when they tear on the mesh.

H319 goes with the five-minute window. Tooling against the clock means working fast with your face close to a bead you are pushing material through. Squeeze-out comes up unpredictably through an open weave. Safety glasses for the tooling stage.

H304 is why the remover does not belong on the workbench. Aspiration hazard Category 1 means that if it is swallowed and any reaches the airways it can cause a potentially fatal chemical pneumonitis — which is why the first aid is to never induce vomiting. It is a beige paste in a screw-top tub that looks like filler. Lid on, stored high, and nowhere near food or drink on the bench.

If you do use it, ventilate. H226 and H336 describe the room, not the product. Canvas repairs get done in sheds and garages with the door shut. Open it, and keep heaters and cigarettes out.

Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions

Will the joint stay flexible?

Roof & Gutter Silicone has ±25% joint movement capability and 330% elongation at break, so the cured silicone itself is very flexible. All Fix Multi Grip is described as remaining flexible to some extent.

Why does the mesh make so much difference?

An open weave gives the adhesive far less area to grip than a solid patch. That is why a product with body that can key through the holes outperforms a thin glue that only wets the strands.

Can I stitch as well as glue?

Nothing in the Selleys advice prevents it, and on a job where the adhesive is working against an open weave, a mechanical fixing carries load the bond may not.

How long before the silicone is weatherproof?

It is tack-free at about 30 minutes but cures through at 2 mm per 24 hours. Do not roll, fold or wet the repair until it has cured through its full thickness.

Can I paint the silicone to match the canvas?

No — Roof & Gutter Silicone is not paintable. It is available in a wide range of colours, so choose one close to your canvas.

How do I clean up excess?

Turps removes wet silicone from tools. Cured silicone has to come off mechanically or with Selleys Sealant Remover — but note that Sealant Remover is not suitable for rubber, EPDM or polycarbonate, so keep it away from anything of that kind nearby.

What if I am patching the canvas itself rather than adding mesh?

That is a different job with a different answer — see how to glue canvas to canvas.