Homebrew PCBs

http://www.mgchemicals.com/products/416dfr.html

I need to buy more negative dry film, and MG just came out with
theirs.  Has anyone used it?  Their web pages say to use potassium
carbonate to develop it, but I'm set up for sodium carbonate.  I
emailed them asking if sodium carbonate would work, but haven't heard
back from them.