batards diagnostic - help

Hello,

A few weeks back I decided to get serious about my sourdough bread... as a french man exiled in the Netherlands it is a necessity. But here it is...how can I improve the oven spring of my batards! What is happening?

Here is what I do:

loafs of 400gr

500gr organic Wheat Flour french T80 (not white, not wholegrain, somewhere in between), it is an ancient bread of wheat, very weak gluten, but great taste.

500gr organic white wheat flour French T65 (12,5% protein)

700gr + 100gr water (approx. 80% hydratation)

100gr levain

18gr salt

T° proofing cabinet 23°C

A. Refreshing Levain 100% hydration to get 100gr of active levain (11H or volum x2)

B. In the morning, second levain,  1/6 of flour + 1/6 water + 100gr active levain T°23C 

C. When volum levain x1.8 (after approx. 3H), start hydrolize of all flour + water

D. When levain doubled in volum (approx. 3,5h),  mix autolyse + levain + salt + 100gr water T°C

E. Slap&fold 10min with some rest

F. Bulk fermentation T°23C for 2,5H with 3 tours

G. Preshaping + resting + shaping 

H. proofing on a couch T°23C for 4h45

I. preheat oven top 270°C / bottom 270°C for 45min

J. baking in a pizza oven top 270°C / bottom 270°C + steaming towel in tray 

K. after 10min reduce heat to 220°C / 220°C

L. open door 10min before end for steam to escape

M. Total baking time 30min

There are a few things I am not sure off:

- what is happening with my scoring, they first stretch, then sort of dry, then explode... you can really see it on the pictures, there is 2 kind of texture around the scores.

- I am happy with the crumb, but overall I'd love more oven spring, what is limiting my oven spring?

- I am using a new oven, an electric pizza oven, 1,5cm ceramic stone, 2x1500W. It is doing a bit better than my old gas oven. I can control the top and bottom heating elements separately. Should I increase the temperature of the bottom?

- The door of the oven has no joint... so the steam can escape. But with the steaming towel technic, there is steam coming out when I open the door after 20min of baking. But do I have enough steam?

Voila, any help is appreciated.

IMG_6747[1].JPG

IMG_6750[1].JPG

IMG_6744[1].JPG