The fact of anything being out of order, forms no excuse for slighting the process.

If unsuccessful, do not pursue the same course every trial, but vary with a view to detect the cause of the difficulty.
In case of a long series of failures, institute a regular course of investigation, after this manner, commencing where the trouble is most likely to occur: 1.

Are the plates well cleaned?
2.

Is the iodine dry?
If the impressions come out blue, you may rest assured it is not.

Take out the iodine, wipe and dry the box, and dry the calcium.
3.