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Filling knife buying guide: width, flex and handle

Updated: 21 October 2026

You are about to fill screw holes, or feather a patch on a ceiling, and the amazon.co.uk Putty Knives aisle has mixed filling knives, putty knives and stripping knives into one scroll. A title that says 2 inch can sit beside a dimensions row that reads 53 cm, and a four-pack can arrive with edges sharp enough to draw blood. This filling knife buying guide orders the decisions: job, width, handle, the steel claim, then listing conflicts, before the price table on the [filling knife comparison](/hub/painting-supplies/filling-knife). Peter F. did not run a lab test. A qualifying purchase through our links can earn us a commission at no extra cost to you.

You are about to fill screw holes, or feather a patch on a ceiling, and the amazon.co.uk Putty Knives aisle has mixed filling knives, putty knives and stripping knives into one scroll.

Our top picks

Axus Decor Axus Decor Pro-Fill

Best overall

Axus Decor Axus Decor Pro-Fill
8.0/10about £5.39
View offer
ROLLINGDOG ROLLINGDOG set

Alternative

ROLLINGDOG ROLLINGDOG set
6.3/10about £25.99
View offer
Harris Harris Seriously Good

Rank 3

Harris Harris Seriously Good
8.5/10about £5.04
View offer
On this page
  1. 1.Flex first, then the name on the packet
  2. 2.Widths a UK decorator actually uses
  3. 3.Handle, edge, and the stainless line
  4. 4.What to do with a conflicting listing

Flex first, then the name on the packet

A filling knife is the thin, flexible blade UK trade counters use to press filler into gaps and leave the repair level. Toolstation separates it from a rigid stripping knife for wallpaper or paint, and from a putty knife with a bolstered hardwood handle. Painters World uses the same split. A stiff scraper drags filler back out of a hole. A floppy filling blade skids on soaked paper. The filling knife or stripping knife page is that versus. ROLLINGDOG is titled wallpaper scrapers while the bullets name spreading filler, so measure the bend. ProDec’s 2 inch filling knife is the contrast: thin stainless, full tang, and the brand says it is not a scraper.

Widths a UK decorator actually uses

Trade sizes here cluster at 2 inch (50 mm), 3 inch (75 mm), 4 inch (100 mm) and, on the Harris pack, 5 inch (125 mm). Narrow blades suit screw holes and fine cracks. A 3 or 4 inch blade feathers a flat wall. Tooled-Up, checked on 21 October 2026, treats 75–100 mm as the everyday width. That is shop copy, not a promise about these four ASINs. Axus Pro-Fill AXU/FKB2 is titled 2 inch / 50 mm while the dimensions row prints 53 cm by 7 cm, and reviews also call the blade 4 inch or, in one title, 25 mm. Amazon pools sizes. Measure on arrival. ZAVIA says four widths and prints neither inches nor millimetres. Harris lists 2, 3, 4 and 5 inch by name.
Axus Decor Axus Decor Pro-Fill

Testsieger

Axus Decor Axus Decor Pro-Fill
8.0/10about £5.39
View offer

Handle, edge, and the stainless line

Harris and ZAVIA are short continental blades with a TPR or plastic grip. Harris reviews, 3,982 of them, say the bare edge cuts fingers. Three of eleven UK reviews on ZAVIA mention cuts. Axus at about £5.39 has a rubber handle. ROLLINGDOG at about £25.99 has beech. Either keeps fingers farther from the steel. All four listings say stainless. Harris aftercare is warm soapy water, then dry completely. Axus reviews that mention rust say the blade did not. Two of eleven UK ZAVIA reviews say rust after water. Dry every blade. No British Standard for filling knives turned up in these sources.

What to do with a conflicting listing

Axus B00NY2DSR8 is the worked example. The title says 2 inch / 50 mm, model AXU/FKB2. MyPaintbrush calls that model 2 inch (51 mm), a width check rather than a new amazon.co.uk price. The same 53 L x 7 W cm line appears on a 6 inch sibling in search, which points to shared catalogue text. Reviews that say 4 inch do not rewrite the title. When the figures disagree, measure and keep the receipt. The Consumer Rights Act 2015 says goods must match their description, including main characteristics the seller states. Stars on a pooled listing can describe another width. Who each listing suits is on the best filling knife page. Press, level, wash and dry is on how to use a filling knife.

Common questions

What width filling knife do you actually need?
For screw holes and hairlines, start near 2 inch or 50 mm once that blade is in the pack. For a flat-wall patch, 3 or 4 inch is the usual trade band. The Harris pack states 2 through 5 inch in one box when you want every width printed.
Is a filling knife the same as a putty knife?
No. Trade pages put the filling knife on flexible steel for filler, and the putty knife on a stiffer blade for window putty and scraping. The Putty Knives aisle mixes both names. Bend the steel. A filling knife gives. A putty knife is the bolstered window tool.
Should you buy one handled knife or a four-width pack?
Buy one handled knife for a rubber grip and a single width you will measure. Axus Pro-Fill is that shape. Buy a continental pack for several widths and sharper bare edges. Harris numbers four sizes. ZAVIA says four widths and does not number them in inches or millimetres.
What if the title says 2 inch and the reviews say 4 inch?
Measure the blade. On Axus the title says 2 inch / 50 mm, the dimensions row says 53 cm by 7 cm, and some reviews say 4 inch. The 4.7 line from 1,393 reviews does not prove which width arrived, because amazon.co.uk can pool sizes.
Does stainless mean you can leave the blade wet?
No. Dry the blade after washing. Two of eleven UK reviews of ZAVIA say rust appeared after water even though the listing says stainless. Harris aftercare, on the listing and on harrisbrushes.com, is warm soapy water and then dry completely before storing.
When is a wood handle worth more than a rubber grip?
When you want beech handles and stated 1 to 4 inch blades, and you accept about £25.99 plus a title that also says wallpaper scrapers. That is ROLLINGDOG. For a first screw hole, a rubber grip on one Axus knife is the simpler choice.

Related pages

Filling knife for wall cracks

Filling knife

Best filling knife: who each of four listings suits

How to use a filling knife: press, level, then dry

Filling knife or stripping knife: flex decides the job

Sources

Public UK sources used for this comparison. Listing prices, stars and review counts are the amazon.co.uk figures saved for these four ASINs. The Harris price was also noted by Morris and Mica on 17 October 2026.

  1. Toolstation, filling and putty knives (retrieved 17 October 2026)
  2. ProDec Advance 2 inch filling knife (retrieved 17 October 2026)
  3. Harris Ultimate 2 inch filling knife (retrieved 17 October 2026)
  4. Polycell Multi Purpose Polyfilla ready mixed (retrieved 17 October 2026)
  5. Toupret, hairline cracks (retrieved 17 October 2026)
  6. HSE, lead in construction (retrieved 17 October 2026)
  7. HSE, sanding plasterboard joints (retrieved 17 October 2026)
  8. Consumer Rights Act 2015, section 11 (retrieved 17 October 2026)
  9. British Coatings Federation, PaintSafe (retrieved 17 October 2026)