I am trying out new paper, Fotokemika, EMAKS graded fiber. I like the rich blacks and brilliant midtones. Fotokemika's limited instructions mentions a fix time of 4-6 min with efke FF-1, a rapid fix. I use TF-4 (film strength) and toss the fix after 10 to 12 8x10s. To accommodate EMAKS I increased my normal 60s fix routine to 120s. The 120s is well short of the manufactures recommended times. I process to archival standards using Ilford's archival fix/wash recommendations. The Fotokemika's recommended long fix times allow the paper to absorb fixer. On the other hand I have a real potential to underfix. How can I determine if I underfix? Any recommendations concerning processing this paper?