I'm prepping my walls for painting. There are various sizes of putty knives and they come in flexible and stiff versions.

I know that I need to get a few sizes for different kind of work: 4", 6" and 10"

My question is when should I use a more flexible blade and when to use a more stiff blade?

I don't want to buy more putty knives than I have to.

1 Answer 1


Flexible "putty knives" find more application when performing operations such as doing drywall taping. Particularly when larger width blades are used such as 6", 8" or 10" sizes.

Smaller sized blades in the 1" to maybe 2.5" sized are more often used with the stiffer blade for operation such as spackling over small areas.

I have found it invaluable to keep a stiff blade putty knife of the following style available. These come with a relatively sharp edge which makes them very useful for scraping down high bumps and removing paint edges that may be left when something like a door stop or base show molding is removed. The flat end nose of this tool also works very well to open spackle and putty can covers.

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  • Why does the flexible blade help?
    – milesmeow
    Jul 11, 2016 at 13:58
  • 1
    Wide blades used for drywall taping want to have flexibility of a number of reasons. Flexible blades are thinner and thus weigh less. It is possible to vary the pressure applied to drywall whilst keeping part of the blade almost flat with the wall. The flexible blade will more easily pull over wall surfaces that have some variations (particularly across seams) than some think thing that feels like a quarter inch thick sheet of steel. There is a good amount of developed technique related to flexible blade use that is hard to describe in words.
    – Michael Karas
    Jul 11, 2016 at 23:26

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