Sourdough always sticks to board

Here are a few things that I discovered:

1. When you are doing the first or bulk ferment, let the dough go until it is jiggly, has lots of smallish bubbles that you can see through the wall of the container and has some bubbles on the top or sides of the dough where it meets the wall of the container. When the dough is at that point, it comes away cleanly from the wall of the container. I used to let my dough go much longer and it stuck to everything. It no longer does that. <--- This tip was key for me to prevent sticky dough.

2. Put the dough on a bare counter. Then put flour on top of the dough. If you need to weigh it, flour the surface of your scale or whatever you are going to put the dough on, and then flip the dough so that the floured side meets the floured surface of the scale. That way, you are only adding flour to one side of the dough. Once you have weighed it, flip the portion again so that the bare part is back in contact with the bare counter. Then use your scraper to round the dough. Since the outside surface is floured, the scrape generally is in contact with that rather than the underneath sticky portion. Use quick movements so the scraper doesn't have a change to stick.

3. After a rest, flour lightly the surface of the dough and a spot on your counter. Flip the dough flour side to floured counter and keep your fingers under the dough where it is floured when shaping. Once you have shaped it, roll it so the seam is down and place on a bare spot on the counter. Do your tension pulls there. I also spin the dough like a top at the end to make sure my boules is nice and tight. Let it sit for a minute or two so that the seam is well sealed under and then place it in your bannetons which every way you want. I place mine seam side down because I bake seam side up (I don't score my loaves, I let them split naturally). 

I hope this helps.

i had similar problems and my first solution was to change the flour I was using which I never would have considered without this site :) I learned that amylase and ascorbic acid are added to a lot of flours (almost all here in Canada) but can really affect lean breads. If your flour has these, I’d suggest finding ones that don’t, it makes a huge difference. 

After changing flours my sourdough was good for a while, then started being crazy, unshapably sticky again in the summer, and that turned out to be the ambient temp. If I put my dough in the basement, which is much cooler in my house, it greatly improved, so if it’s really warm wherever your resting your dough, that might be another culprit.

hope you’re able to figure out the cause, I know it can be really frustrating....