Fillers

Commercial Fillers

These are by far the most popular fillers. Commercial fillers are ready made, and formulated to avoid the defects sometimes present with diy-made fillers.

Some of the materials on the Putty & Mastic page are used as fillers for various purposes, so there is some overlap between the two.

Dry fillers

Polyfilla, Tetrion, etc are dry powder fillers. These store for years after opening (in dry conditions), and are thus good where filler is only occasionally used in small amounts. They are made of assorted powdered aggregates plus EVA or similar glue.

Mix them stiff for bulk filling, and mix soft and smooth for fine surface filling.

Ready mixed Tub fillers

These are the most popular type. No work is needed, open the tub and use. However they don't keep well once opened.

Fine surface filler gives a finer finish, but cracks from shrinkage if used for deeper holes.

Artex is often used as a filler, and is cheaper than other types of ready made filler in large amounts.

Cartridges

Decorator's filler in 310ml cartridges is an easier way to fill long gaps, such as corner cracks in plaster.

Nomorenails, gripfill and the like can be used as tougher fillers. These come in water based and solvent varieties.

Acrylic sealant may be used as a filler if necessary.

If sealed well after use, cartridges are sometimes re-usable later. Aluminium foil makes a better water vapour barrier than polythene, and a tight tie seals better than just wrapping foil on loose.

Expanding Foam

Fills large holes. Can be used where access is difficult, since it expands after application. Excellent thermal insulation, but the finish the foam leaves is a mess.

Often used to fill large holes, eg around pipes, the foam accomodates small amounts of movement.

Beware of forceful expansion after setting; this material can apply surprisingly high forces if restrained, with potential for considerable damage.

Expanding foam deteriorates quickly when exposed to UV. Completely cover it the next day if used outdoors.

Foam is flammable and produces toxic smoke in a fire. Fire retardant foam is available.

The wet foam is adhesive. The canisters drip foam after the trigger is released, due to expansion in the dispensing mechanism.

Expanding foam use can go very wrong.

• Misused as cavity insulation it can bring down masonry walls with its expansive force.
• Unexpected expansion can cause all sorts of problems (canoe link)
• Expanding foam seems to be popular with bodgers.
• Some people have even died using it.

Wood Fillers

Linseed putty may be used to fill wooden windows. It is very slow setting.

Alkyd putty is similar but sets sooner.

Water based putties are much quicker setting, but final strength is less. They are available in various tints to match wood species.

Matching filler colour to pine is somewhat impossible, as pine changes colour over a wide range over time. Hence pine is sometimes left unfilled when not painted.

Resin Fillers

These are high strength adhesive fillers used where durability is important.

Car body filler is a tough Polyester resinpreparation with numerous DIY uses, both as filler and adhesive.

• filling wood windows
• filling steel windows
• list filler uses

Epoxy resin may be used to fill small holes in tiles. It is mostly used as glue rather than filler. Clear epoxy is available.

Epoxy cement is used to fill holes in concrete floors. It contains epoxy resin and aggregate, and is tough and fairly quick setting.

Lightweight Filler

A recent development in fillers is the introduction of 'lightweight fillers' sold under the brand names Red Devil ONETIME Filler, Everbuild One Strike, Wickes Fast Fill etc. They apparently contain lightweight polymer bubbles. These do not crack, shrink, or sag and require little or no sanding. They can be overpainted in 30 minutes or so. They reflect light differently to plaster, and this can show through emulsion.

Others

Leftover tile adhesives & grouts can be used as fillers. They tend to set pretty hard, as a lot are cement based, so should be treated as non-sandable.

Ad Hoc Fillers

About Ad Hoc Fillers

Fillers are elementary to make from a fair range of available ingredients, and cost is negligible. These fillers tend to be used on 'back to nature' type projects, or when bought filler has run out.

Many DIY filler formulae can be used. In practice these fillers are often made up from whatever suitable materials are to hand.

Fillers contain 2 essential components:

• a glue of some sort
• a bulking agent

Some also contain some form of fine aggregate to stop shrinking, such as sand or masonry dust.

1, 2 and 3 Component fillers

In some fillers, one material is both bulk and glue. Rice is an example of this. 1 component fillers work ok as shallow surface fillers, but when used in significant depth they shrink and crack badly.

2 Component Fillers use 2 separate materials for glue and bulk.

Suitable water based glues include:

• wallpaper paste
• lime
• cement
• PVA
• Some carpet glues

Any of a wide range of bulking materials may be used.

• chalk
• lime
• Subsoil
• Sawdust
• most dusts & powders

3 Component Fillers are 2 component fillers plus added coarse non-shrinking aggregates, such as sand or masonry debris. The extra aggregate stops significant shrinking, thus enabling filling of deeper holes. The tradeoff is that such mixes are not sandable, and too coarse to give a smooth finish.

Ad Hoc Filler Mixes

Lime & chalk

1 part lime to 2-3 parts chalk is a simple sandable filler. Chalk can be made by leaving lime powder exposed to air for a while, so both components can come from the one bag. Once mixed this will keep indefinitely if not exposed to air. This makes an easily sanded decorator's filler.

The mix is alkaline, and repeated all day use can irritate skin.

Sawdust & diluted PVA

A coarse wood filler. Sandable, drillable, but not the strongest.

Oil putty

Oil based putties can be used to fill wood outdoors. Drying is very slow. Ongoing smell while drying precludes indoor use.

Linseed putty is easily made from boiled linseed oil and chalk.

Alkyd putty may be made from oil based paint and chalk.

Other fine inert powders can be substituted if necessary.

Burnt sand mastic

Also known as Scotch mastic, this is a traditional filler long used for filling gaps around window frames. It is made from burnt sand and boiled linseed oil. It is very slow setting, it smells (very nicely) until set, and can sometimes be eaten by birds while wet. The sand colour blends in well with most masonry, its very tough once set, and accomodates some degree of movement.

See also Putty & Mastic#Burnt sand mastic

Rice

Rice is a low quality filler with just one advantage: its present in most households.

Starch based fillers such as rice may be eaten by rodents, and cao go mouldy if damp. They are not good choices for near ground level use, or for potentially damp locations.

Rice makes 2 types of filler.

Coarse bulk filler:

• Ground rice is mixed with water to make a stiff mix
• This can be used for bulk filling
• Cracking occurs, but the final layer of finer filler will fill the cracks.

Fine finish filler:

• Rice is ground for longer to make it fine.
• Rice is mixed with water to make a smooth softer mix
• This forms a smooth surface, and is good for shallow filling only

See Also

• Putty & Mastic
• Adhesive
• Wiki Contents
• Wiki Subject Categories