<p>In case Thomas is still searching for the answer to this density gradient problem, here's a piece from a couple of years ago that refers to the need to stable temperature, to avoid the gradient: <a href="http://www.japancamerahunter.com/2013/10/black-white-film-development-lazy-people/">http://www.japancamerahunter.com/2013/10/black-white-film-development-lazy-people/</a><br>
<br />I've never tried stand development myself; I just found this article when looking for info about it.</p>