Tartine with malted wholegrain bread flour?

Although Hovis own the trademark on Granary...

Its somewhat irritating that Bakerybits don't list the ingredients, but from what I can see, it's just ordinary brown (stoneground/wholemeal) flour with malted wheat flakes added. So the flour isn't malted, it's got malted grains added. See: http://www.redbournburymill.co.uk/The-Mill/Milling/Flour

I don't use that, but I do use Shipton Mills three-malts and sunflower seed flour a lot in my sourdoughs.

So what to be aware of is the amount of non-flour stuff in the flour - ie. grains, seeds. These will need a bit of water to soak up, so I always end up making a wetter than usual dough then in the morning it's "normal" as the overnight ferment has allowed the grains, etc. to plump up a little.

Shipton mills flour has about 12% extra stuff in it (I sifted 500g once and weighed it!)

But at the end of the day, just give it a go. Just don't make the dough too dry although if you're into Tartine/Forkish hydration levels then you might well end up with a rather sticky mess to play with :)

My usual with Shiptons is 800g flour, 320g starter @ 100% hydration, 435g water, 12g salt. On paper that works out at about 62% overall hydration - and it might well be in the morning once the seeds, etc. have soaked up the water. It's a bit of a sticky mess on the bench! My technique for this: mix everything in a bowl, turn it out onto the bench, mix more on the bench. Pull into a pile, cover with the bowl. Leave it alone for half an hour (ie. autolyze with everything in it), and as if my magic it will settle down and pass the stretchiest of window pane tests. I give it a very quick knead at that point which tightens it up into a ball, leave it in the bowl to rise overnight, scale/shape/prove in the morning and bake!

http://moorbakes.co.uk/wp-content/uploads/2013/09/maltster1.jpg

-Gordon