</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (c6h6o3 @ Nov 17 2002, 10:37 PM)</td></tr><tr><td id='QUOTE'>No error in film rating or agitation procedure could account for such a difference.
</td></tr></table><span id='postcolor'>
I disagree, if David is rating the film at 100 and the EI he needs is 400 then there is two stops right there. If this is compounded with high overall staining for which HP5 is known for, I can easily see a 4 stop difference in density. I use HP5 as well as TMY 400 for my 8x10 and see a marked difference in overall and b+f staining between both films, HP5 being much greater than TMY.

As I understand it he is already using the pyro from Artcraft, thus his questions about the purity grade. I believe the problem lies with the mixing of the chemicals. Without knowing how much David put in each solution the most likely problem is oxidation of pyro and high overall staining.