Davy's Gray and Payne's Gray

Paynes' Gray:

Davy's Gray:

Pigment numbers:

Payne's Gray - PB15 + PBk6 + PV19

Davy's Gray - PG17 + PBk6 + PBk19 + PW5

The two Grays

Payne's Gray is a dark blue grey. This is a very transparent, dark paint with a wide tonal range which Anna uses A LOT! However, it's a very intense colour and therefore in order to get a really pale colour when you use it, you need to add lots and lots of water to it and often you'll need to add a touch of Yellow Ochre or Burnt Sienna in order to create a warmer, less blue, hue. Anna also uses Payne's Gray to darken other colours.
Davy's Gray is a semi-transparent, soft grey colour. This is more neutral in hue than Payne's Gray and is a lighter paint altogether, BUT it's more opaque so doesn't lend itself to layering as well. It's very useful for working on shadows and very small areas such as stamens where you don't want to be working with very watery paint, but you do want it to be light in tone.

When to use Davy's Gray

When you're wanting to work with subtlety more easily: When wanting to use a warm pale grey in a tutorial, Anna will sometimes recommend using Davy's Gray as it does not need to be watered down quite as much or mixed, thus making it a little easier to achieve the desired effect when painting subjects such as the White Cosmos and the Apple Blossom. In the Scallop Shell tutorial, Anna teaches you how to paint with super pale layers so in this case, she opted for the Payne's Gray / Burnt Sienna combo as a learning tool.
When you don't want to risk using watery paint in case of a darker colour bleeding in. For example, when painting the grey detail in the stamens of a brightly coloured flower - you might not want to work with the very watery Payne's Gray / Burnt Sienna combo in case it makes the bright colour of your flower bleed into it. In this case, some thicker, drier Davy's Gray would work well. Anna does this in the Clematis tutorial.

Recommended substitutes

Payne's Gray

Daniel Smith: Payne’s Blue Gray (If you have the Daniel Smith 'Payne’s Gray' you’ll need to add a touch of French Ultra Marine to match exactly if following a tutorial). Make sure any alternatives that you use have a lot of blue in them otherwise you'll not get the same result.

Davy's Gray

Mix 40% Payne's Gray and 60% Burnt Sienna but really watery to match Davy's Gray.
Daniel Smith: Use a mix of 80% Buff Titanium (Daniel Smith) with 20% Payne’s Blue Gray (or Payne's Gray if you have the Winsor & Newton Payne's Gray)

As well as appearing Anna's 'Essential Range' of top 10 paints, Payne's Gray features in Anna's Limited Palette of 6 paint colours.