best flexible filling knife

Best Flexible Filling Knife in the UK (2022 Reviews & Buying Guide)

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Filling knives are an unglamorous but essential component in any serious DIYer’s tool bag. In this guide, I’ve spent several hours researching and reviewing the top three filling knifes available in the UK.

I’ve also provided a handy buying guide so you can find the best flexible filling knife for your specific needs.

In a Hurry? Here’s our top pick for the best flexible filling knife in 2022:

Draper 82660 Soft Grip Filling Knife, 50 mm Blade Width
  • A fully polished flexible steel blade
  • High quality stainless steel blade for durability
  • Soft grip handle for comfort in use
  • Consistent beading and sharp edge for getting into corners
  • Ideal for inserting filler into cracks or holes in wood or plaster

It’s only once you’ve tried to fill a crack or smooth a rough edge without one of these flat spatula-type knives that you appreciate how valuable they are. Our recent guide to smoothing walls without plastering demonstrates this point neatly.

A quality filling knife, such as the Draper 82660, justifies the extra money it costs. Available in various sizes and featuring a precision ground blade that’s been hardened and tempered, the 82660 is the ideal companion for a night on the tiles (or getting plastered).


Best Flexible Filling Knife – 2022 Reviews (The Top 3)

These are our picks as the best flexible filling knives on the market, starting with one which is beyond reproach.

1. Draper 82660

Draper 82660 Soft Grip Filling Knife, 50 mm Blade Width
  • A fully polished flexible steel blade
  • High quality stainless steel blade for durability
  • Soft grip handle for comfort in use
  • Consistent beading and sharp edge for getting into corners
  • Ideal for inserting filler into cracks or holes in wood or plaster

It’s only cost which prevents Draper’s range of soft-grip filling knives from achieving an extremely rare 10/10 score in Property Workshop testing. 

Available in five sizes, from 32mm to 125mm, Draper’s designers have thought of everything. 

The handle is ribbed at the sides, ridged at the top and has three finger grooves at the blade end, with a circular hanging hole for storage. 

The stainless steel blade is polished, precision ground, hardened and tempered, offering an impressive degree of flexibility yet remaining unyielding under pressure.

People who’ve used the Draper range for some time report no issues with quality, with terms like “sturdy” cropping up repeatedly. Sometimes it’s worth paying a little bit more for a quality product.

ProsCons
It comes in five sizesFar from the cheapest product
Superbly ergonomic handleIt may be too bendy for specific scraping tasks
Impressive blade engineering 

2. Silverline 589702

Silverline 395012 Expert Filling Knife 50 mm
  • Corrosion-resistant spring-tempered 50 mm steel blade
  • Two-tone soft-grip handle
  • Moulded palm grip
  • Hanging hole
  • For smooth application of fillers

Silverline’s entry would probably have come top if the price was a deciding factor in this test.

At roughly half the cost of its two rivals, it represents exceptional value for money. However, since the other products are affordable, that benefit isn’t enough to outweigh a few areas where Draper manages to pull ahead.

For one thing, the Silverline’s injection moulded polypropylene handle isn’t as contoured and lacks the quality grip of our test winner. 

Similarly, the choice of 50mm or 75mm blades is the most limited of our triumvirate – Stanley offers a 100mm blade while Draper’s largest product is 125mm.

Even so, there’s plenty to like about this product. Its corrosion-resistant spring-tempered steel blade has a mirror-polished finish, tapering to just 0.6mm along the blade edge. It also features a hanging hole for storage, and its relatively stiff blade makes it an ideal scraper.

ProsCons
By far the most affordable product on testRelatively inflexible blade not always great for filling
Corrosion-resistant mirror-polished bladeLimited choice of sizes
Features a hanging hole 

3. Stanley Dynagrip

Sale
Stanley Dynagrip Filling Knife 50MM 0 28 655
  • High grip contoured handle
  • Comfort and efficiency in use
  • Fully ground flexible stainless steel
  • Easy-to-clean and rust-free
  • Suitable for smoothing filler

For some people, the Stanley name alone will be enough to elevate this 50mm filling knife to the top of their shortlist. 

If you’re already a brand loyalist, this is a quality product, but it does fall short compared to the Silverline and – in particular – the Draper.

For one thing, there are only two blade widths on offer. For another, the handle is an undoubted weak point; its three shallow channels at either side and battery cover-style ribbing beside the blade are underwhelming compared to the Draper’s heavily contoured and grippy handle. 

It’s also relatively heavy at 109g, which won’t strain your biceps but is the heaviest of our three tested knives by a distance.

That said, Stanley does know how to assemble a quality product. The blade is fully ground stainless steel, with a smooth rust-free finish that’s easy to clean. 

You’ll be able to spot that dayglo Stanley badge even in low light, and there are no concerns about this product’s long-term durability.

ProsCons
Well-built and durableHandle lacks texture and grip
Rust-resistant stainless steel bladeHeaviest product on test
Forms part of a far wider DIY tool range 

Best Flexible Filling Knife – 2022 Comparison Table

ModelSizesHanging hole? Blade material Price Rating
Draper 826605YesStainless steel££9
Silverline 3950122YesCarbon steel£8
Stanley Dynagrip2NoStainless steel££7

Filling Knife Buying Guide

When shopping for the best flexible filling knife, always consider the key features below:

Blade Size

worker with filling knife working on apartment wall filling

Like paintbrushes, filling knives come in a variety of shapes and sizes. 

We’re testing three 50mm models, which deliver an optimal balance between covering a decent area and not feeling unwieldy in hand. However, all three of our chosen manufacturers offer different sizes.

We were particularly impressed with Draper’s range, extending from 32mm to 125mm. By contrast, Stanley and Silverline only offer one size larger than 50mm with nothing smaller for more intricate DIY jobs.

Pro Tip: It’s worth having a conversion calculator/chart in front of you when choosing a filling knife. The blade widths of our three selected products are measured in millimetres, but rival manufacturers like Axus list in inches – a two-inch blade would be roughly equivalent to the 50mm products on test here. Always remember there are approximately 2.5 centimetres in 1 inch.

Flexibility and Comfort

filling up grout between red ceramic tiles using filling knife

Their uniquely flexible blades make filling knives great for forcing filler into the smallest crack or crevice. 

A single blade can be suitable for various jobs, providing it’s comfortable to hold and use in different positions. That’s why we’ve chosen three products with heavily contoured handles, designed for a firm grip. Once again, Draper’s filling knife has the most textured handle.

Pro Tip: If you’re not familiar with the art of achieving an optimal consistency when preparing plaster, this guide to mixing plaster explains everything you need to know.

There’s a balance to be struck with these products between firmness (which is ideal for scraping) and flexibility (which is necessary for filling). 


Best Flexible Filling Knife – Final Thoughts

You might be brand-loyal towards Stanley or appreciate the Silverline’s blade’s relative inflexibility. Both knives are good, but Draper’s contribution is genuinely exceptional.

From the Draper’s heavily textured handle to its precision ground and tempered blade, this is a quality product by any measure or definition.

We have no hesitation in declaring the Draper Filling Knife a worthy test winner.

Draper 82660 Soft Grip Filling Knife, 50 mm Blade Width
  • A fully polished flexible steel blade
  • High quality stainless steel blade for durability
  • Soft grip handle for comfort in use
  • Consistent beading and sharp edge for getting into corners
  • Ideal for inserting filler into cracks or holes in wood or plaster