Bottom crust hard to cut
My sourdough bread has been consistently good -- good enough that I've started to sell it! I bake in a dutch oven at 450 degrees -- 30 minutes with a lid, 15 minute without. I use parchment paper on the bottom. I am happy with the crumb, the crust, the ear, and most importantly the taste, but the bottom crust is always a little tough to cut. I bought a new serrated knife that does a much better job, but even so it is still hard to cut. And most people don't have such a high quality bread knife. Often I have to tip the bread on its' side, and saw through the crust.
I read somewhere that putting a sheet pan on the bottom of the oven could help, but when I tried that there was no discernible difference.
Anyone have any ideas? I am wondering if maybe I should try baking at 425? I've used a thermometer, and my oven seems fairly true to its temperature.
Any words of wisdom would be appreciated!