Plastering Trowels: How to Choose, Break In, and Skim With the Right Steel
The UK guide to plastering trowels. Carbon vs stainless, sizing, the five-pass sequence, pre-worn blades, breaking in, and what to buy from £5 to £72.
You're skimming the patch you cut for the consumer unit when the trowel leaves two faint parallel lines down the wet plaster every pass. You go over them. They come back. By the time the plaster sets, the lines are baked in and the only fix is to sand them out and skim again. The trowel was new, straight out of the packaging. Nobody told you the corners on a fresh blade are sharp enough to leave tramlines until they're rounded off, and that ten minutes with sandpaper would have prevented the entire afternoon.
What it is and when you need one
A plastering trowel is a flat rectangular steel blade with a handle on top, used to apply, flatten, and polish wet plaster onto walls and ceilings. The blade is roughly 11 to 16 inches (280 to 405mm) long and 4 to 5 inches (100 to 130mm) wide, mounted on a tang bonded to a die-cast aluminium block under the handle. The handle is wooden, rubber, or cork.
It's also called a finishing trowel, skim trowel, or skimming trowel. "Plastering trowel" is the general term; "finishing trowel" usually means the version used in the final passes where blade flexibility matters more than rigidity. The vocabulary is loose because the same blade often does both jobs in a homeowner-grade kit.
You need one whenever you're applying a skim coat (the thin top layer of plaster that takes paint) or making good a patch around a chase, back-box, or pipe penetration. On an extension build you'll meet plastering at second-fix, after first-fix electrics and plumbing, plasterboard fix and tape-and-jointing. The plasterer mixes Thistle MultiFinish (or similar gypsum finish), applies two ~1mm coats over every wall and ceiling, and the trowel lays it on, flattens it, and polishes it matt smooth.
For a homeowner project-managing a build, you'll almost certainly hire a plasterer rather than skim entire rooms yourself. Where you'll actually pick up a trowel is the patch work around plasterers: the chase you cut for an extra socket, the gap where the spark drilled a cable, the damaged area behind where kitchen units used to sit. These are 200mm-square jobs where a budget carbon trowel from the £5 – £15 tier is cheaper than calling the plasterer back.
Carbon, stainless, or plastic
Trowel blades come in three materials. Each one suits a different task and a different user. Buying the wrong one is the most common reason a beginner's first attempt at skimming goes badly.
Carbon steel is the traditional plasterer's choice. Hardened tempered carbon flattens in fast, takes a sharp working edge, and produces an excellent finish in skilled hands. The downside is rust: a carbon blade left damp will be mottled with brown spots by morning. After every use it needs wiping clean and a quick coat of WD-40 to seal the surface. Carbon trowels also need breaking in before first use. The £5 – £15 tier covers entry-level Silverline and Magnusson carbon; mid-range carbon options like the Ragni soft-grip 14-inch sit in the £20 – £35 band.
Stainless steel is the modern default. Stainless never rusts, takes less daily maintenance, and is the only sensible choice for gypsum-based plasters (the standard UK skim). Carbon can cause faint oxidation marks on white gypsum finishes that show through pale paint. The trade-off is that stainless takes longer to "wear in" to a sharp working edge, and pure stainless blades historically felt slightly less responsive than carbon. That gap has closed with modern German-made stainless from Refina and Nela. Forum surveys suggest more than 80% of working plasterers now prefer stainless.
Polymer (plastic) trowels are a specialist finishing tool, not a general-purpose one. The Refina Plaziflex is the dominant brand: a flexible polymer blade with interchangeable sleeves in 1.0mm, 1.5mm, and 2.0mm. On the final wet trowel pass over a flat wall it reduces watermarks and gives plaster a slight glow steel can't match. Used during laying-on or flattening it ripples the surface, and it damages easily on corner beads and metal reveals. Treat polymer as a third tool, not a replacement for steel.
Pre-worn versus flat blade
Walk into Screwfix and you'll see two near-identical Marshalltown trowels at very different prices. One is the standard carbon model. The other is the PermaShape Gold, a stainless model with a slight curve already pressed into the blade and bevelled edges already rounded off. The price gap reflects the work done at the factory, not the steel.
A brand-new flat trowel has square corners on every edge. Square corners dig into wet plaster and leave fine parallel tramlines on every pull. To stop this, the corners need rounding off, either at the factory or by the user with sandpaper or an oilstone. This is breaking in. On a budget carbon trowel it takes ten minutes with 400-grit aluminium oxide paper: round the four corners and feather the edges so they're smooth to a fingernail run.
Pre-worn blades skip this. The Marshalltown PermaShape, Refina Finatex, and Faithfull Prestige all arrive ready to skim. For a homeowner doing one or two patches, a pre-worn stainless at the £25.80 mark (Faithfull Prestige) or the £67 – £73 band (Marshalltown PermaShape) saves an evening of preparation and removes the most common cause of beginner mistakes.
Sizing
Trowel sizes are quoted by blade length in inches: 11", 13", 14", and 16" being the four sizes you'll commonly see on UK shelves. Width is roughly 4 to 5 inches across all sizes. The size you want depends on the area you're working and the strength of your wrist and shoulder.
| Size | Best for | Skill level | Notes |
|---|---|---|---|
| 11 inch | Patch repairs, ceilings, awkward corners, small bathrooms | Beginner | The easiest size to control. Recommended first trowel for any homeowner doing one-off DIY work. |
| 13 inch | Standard rooms, mixed wall-and-ceiling work | Intermediate | The traditional plasterer's workhorse for decades. Slightly easier to wield than 14 inch. |
| 14 inch | Standard rooms by skilled users, the all-day default | Intermediate to pro | The current most popular size with working plasterers. Best balance of speed and control if you can handle the weight. |
| 16 inch | Large flat walls, full-room skim by experienced plasterers | Pro | Faster coverage but only if your technique is solid. Beginners actually finish more slowly with a 16 because they lose control of the blade. |
The temptation for a first-timer is to buy the biggest trowel on the shelf, on the logic it covers more wall per pass. The opposite is true. A 16-inch blade demands strong wrist and shoulder control to keep flat against the wall at a consistent angle. Beginners can't hold that angle, the blade rocks, pressure varies, and the finish ends up worse than a smaller trowel would produce. Start with 11" or 13" and upgrade later.
For ceiling work, drop a size from your wall trowel. A 14" feels manageable on a wall but punishing overhead because gravity adds to the wrist load.
How to skim with one
Skimming is a five-pass process spread over forty to sixty minutes per coat. Plaster is mixed to the consistency of double cream, poured onto a spot board (a square of plywood at hip height), scooped onto a hawk, and transferred to the wall in flowing arcs. The trowel does the work in five stages.
First coat: laying on
Hold the rigid trowel at roughly a 30-degree angle to the wall. Push plaster up the wall in long strokes, starting at the bottom-left corner of the area and working up and across. Aim for an even 1mm to 2mm thickness across the whole wall in this pass. Do not try to get a perfect surface yet. Cover the area, get the plaster on the wall, move on. Coverage and thickness are the goals here, not finish.
First flatten
As soon as the laying-on coat is fully on the wall, flatten with the same rigid trowel held closer to the wall (roughly 15 degrees). Pull the blade across the surface in long horizontal sweeps, applying steady even pressure. Imperfections from the laying-on pass close up. The wall starts to look flat. Use the rigid trowel for this, not a flexible one. Flexible blades flex unevenly under flattening pressure and produce ripples (plasterers call them zebra stripes).
Apply the second coat (laying on)
Mix the second coat slightly thinner. Apply with the rigid trowel exactly as before, building another 1mm to 2mm over the now-firm first coat. Use the same low-angle laying-on motion. The second coat fills the residual marks from the first.
Second flatten and first trowel-up
Once the second coat is on and starting to firm (the touch test: press a fingertip against the surface and it leaves a damp print but no plaster lifts off, usually 10 to 15 minutes after laying on), trowel-up. This is the first finishing pass. Use a medium-flex trowel if you have one (Refina Superflex 2 or Nela Mediflex are the common choices), otherwise stay with the rigid trowel and accept slightly more effort. Pull the blade in long passes, slightly overlapping. The surface should start to glaze.
Wet trowel and dry trowel
After another 10 to 15 minutes (the touch test now leaves only the faintest mark and the plaster is hard but not dry), do a wet trowel pass. Dip a clean brush in fresh water, splash a light film of water across the wall ahead of the trowel, then trowel the surface with a flexible blade (Refina Superflex 1 or a Plaziflex). The water lubricates the final compaction. Last pass is the dry trowel: no water on the wall, just a final firm sweep with the flexible blade or a Plaziflex to polish out any remaining marks. The finish should be matt and smooth, not shiny. A shiny finish is over-polished and resists paint.
Tip
The single most important skill in plastering is knowing when to stop. Beginners trowel too long, working the plaster after it's set, which pulls material away and creates the pock-marked finish that has to be sanded back. Professionals describe the core skill as "knowing when to walk away from it and leave it alone". Apply, flatten, wait. The plaster does most of the work as it pulls in.
Warning
Never use ultra-flexible trowels (Refina Superflex 1, Plaziflex) during the laying-on or flattening stages. Flexible blades bend unevenly under the high pressure those stages need, producing wavy stripes (zebra stripes) that bake into the finish. Flexi trowels are for the final two passes only, when the plaster is firm enough to support a light finishing touch.
Breaking in a new trowel
Skip this section if you bought a pre-worn blade (PermaShape, Finatex, Faithfull Prestige). The factory has done the work.
For a budget or standard carbon trowel, breaking in takes ten minutes with 400-grit aluminium oxide sandpaper. Lay the trowel face-down on a flat surface. Run the sandpaper in small circles over each of the four corners, rolling the corner over until the sharp 90-degree edge is a soft radius you can run a fingernail across without catching. Feather the long edges to take the burr off. An oilstone gives a slightly cleaner result in twenty minutes if you have one.
A traditional alternative is to use a new carbon trowel on render (sand-and-cement) for three to six months before promoting it to skim work. Render is rougher than gypsum and breaks the blade in naturally. For a homeowner doing one patch, the sandpaper method is the right call.
What to buy
Pricing is well-bracketed: budget carbon at the £5 – £15 mark, mid-range stainless in the £20 – £35 band, professional pre-worn stainless from the £40 – £47 Nela tier up to £67 – £73 for Marshalltown PermaShape. There is no high-end market beyond that because a working plasterer would buy two trowels rather than one premium one.
Budget tier
Budget carbon plastering trowel (Silverline, Magnusson, Amtech, Toolstation Minotaur)
£5 – £15
The Silverline 280mm carbon trowel is the cheapest viable starting point: hardened tempered steel, wooden handle, five-rivet fixing. Needs breaking in and oiling after each use. The Magnusson range at Screwfix runs across all four sizes in carbon steel. The Toolstation Minotaur 11" is similar. Adequate for one or two patch repairs.
Mid-range tier
Mid-range carbon and stainless trowel (Ragni, OX Pro)
£20 – £35
The Ragni soft-grip skimming trowels are the sweet spot for serious DIY. Ragni is a UK manufacturer with a long reputation. The OX Pro 14" stainless is a step up: thicker blade, better-finished edges, soft-grip handle.
The Faithfull Prestige 14" stainless at £25.80 is the dark horse: pre-worn out of the box, 301-grade stainless, 0.6mm blade thickness, and a 10-year guarantee. For a homeowner buying one trowel for a lifetime of patch repairs, this is the best value-per-pound option on the UK market.
Professional tier
Marshalltown PermaShape Gold pre-worn stainless (13-16")
£67 – £73
Three brands dominate. Marshalltown is the global default. The PermaShape Gold 14" stainless is the most-recommended professional trowel in UK forums: pre-worn, gold-coloured stainless coating (easier to see against wet white plaster), bevelled edges, DuraSoft handle, one-year warranty. Some plasterers describe PermaShape as "Marmite" because the pre-pressed curve doesn't suit every style, so try before committing.
Refina is the British favourite, with a Superflex range covering laying-on (Superflex 3, rigid), flattening (Superflex 2, medium), and finishing (Superflex 1, ultra-flex) at £55 – £80 depending on size and handle. The Refina Plaziflex polymer trowel at £30 – £45 is a separate purchase but pairs well with a steel Superflex for the final two passes.
Nela is the German underdog. The Nela Premium 14" at £40 – £47 has a cork handle, a die-cast aluminium mounting block, and a bevelled blade ready to use. The best stainless professional trowel in this band.
What to actually buy
Plastering trowel + hawk + bucket beginner kit
£40 – £100
For a one-off patch: Silverline 280mm carbon plus ten minutes with sandpaper. Bottom of the budget tier.
For a homeowner who'll come back to plastering occasionally: Faithfull Prestige 14" stainless. Pre-worn, lifetime guarantee, no maintenance.
For a homeowner planning to skim a whole room: Marshalltown PermaShape Gold 14" plus a Refina Plaziflex. Use the PermaShape for laying-on and flattening, the Plaziflex for the final wet and dry passes. Less than the cost of one room re-skimmed after a botched DIY attempt.
External resource
Refina trowel range
Full UK product line with current prices, blade thicknesses, and handle options. Useful reference for understanding why working plasterers run two or three trowels rather than one.
refina.co.uk
Pairing with the hawk and float
A trowel is the central tool but never the only one. Three companion tools complete the kit.
A plastering hawk is the square handheld platform that holds plaster between the bucket and the wall. Match the hawk size to the trowel size: 13" trowel with 13" hawk, 14" with 14". A mismatched pair makes loading the trowel awkward.
A plastering float is a wooden, plastic, or sponge-faced flat block used for floating the surface of base coats (browning, hardwall, render) before the skim coat. A float is for base coats; a trowel is for skim coats. Don't confuse them.
A spot board sits on a stand at hip height and holds the working batch of plaster. A 600mm marine plywood square on a Trestle is the standard setup. Without one you're bending over a bucket every twenty seconds.
Looking after the blade
A trowel that's looked after lasts decades. The maintenance is simple.
After every use, scrape plaster off the blade with the edge of a second trowel before it sets. Set plaster pits the steel underneath. Wash the blade in clean water, dry it with a rag, and (for carbon only) wipe a thin film of WD-40 over both faces. Hang by the eye on the handle or store flat on a shelf, never on the blade edge.
Stainless needs wash-and-dry but no oil. Polymer just needs a wash.
Never leave plaster on a trowel overnight. Never bang the blade on the spot board to clean it (this dents the corners and undoes any breaking in). Never use the trowel as a scraper for old paint or grout: it's precision-finished steel and loses its working geometry quickly.
Where you'll need this
- Plastering - the primary tool for laying on, flattening, and finishing skim coats over the whole room
- First fix electrics - patching chases and back-box cut-outs after first-fix is done and before the plasterer returns
Plastering trowels turn up at second-fix on any extension, loft conversion, garage conversion, or renovation project where walls and ceilings are being skimmed. Even on builds where a professional plasterer does the heavy work, the homeowner often picks up a small trowel for patch repairs around added sockets, displaced switches, or post-skim damage from kitchen-fitting.
Common mistakes
Buying a 16-inch trowel as your first one. The bigger the blade, the harder it is to keep flat against the wall. Start with 11" or 13", build technique, upgrade later if you actually need more coverage.
Skipping the breaking-in step. Sharp factory corners leave parallel tramlines on every pass. Ten minutes with 400-grit sandpaper before first use saves an afternoon of repair work. Skip the step entirely by buying a pre-worn blade.
Using a flexi trowel for laying on. Flexible blades ripple under the pressure needed for laying on or flattening. The result is wavy stripes baked into the finish. Flexi trowels are finishing-only. Use a rigid trowel for the first two passes.
Leaving plaster on the blade. Set plaster pits the steel underneath and accelerates rust on carbon blades. Wipe and wash the blade immediately after each session, every time.
Pressing harder during the second-pass trowel-up. Beginners assume more pressure means a smoother finish. The opposite is true: heavy pressure on a setting plaster pulls material off the wall and creates the pock-marked surface that has to be sanded back. Light, consistent pressure with the correct angle does the work. The plaster does the rest as it pulls in.
Using stale water for the wet trowel pass. Old water in a bucket has plaster dust dissolved in it from previous mixes, which speeds the set unevenly. Use fresh cold water from the tap for the wet trowel.
Treating polymer trowels as a steel substitute. A Plaziflex is a finishing tool for flat walls without beads or reveals. Used to lay on plaster, or used near a metal corner bead, the polymer blade scratches and the finish suffers. Keep polymer for the final passes only.