I have use this protocol to stain SDS-gel. "But why do you use so high
concentration of glutaraldehyde(10%)", my colleage in once asked me. So I
reduce the concentration to 1% or even 0.5% of glutaraldehyde and get the
same result. By using a shaker and raising temperature, the time for each
step may be reduced to half of the original and the stain may be finished
in 2 hour.