Shibori piece

The shibori piece was finished, with a facing, signed, and had a sleeve attached.  ( I still haven't come up with a title. any suggestions?) My husband made a dowel hanger for it and we hung it on the wall.  Then the more I looked at it the more I realized something was wrong.  Since any problems I have are usually related to value, I finally figured out that the angled line from bottom left to upper right was not obviously not complete. The portion on the left lacked enough value difference to be seen at a bit of a distance.  I reconciled myself to having to darken that line, which is only about 1 1/2" wide.How could this be darkened without any colour spreading or wicking into the adjoining areas or through to the back.

I decided to take a picture and post it here, asking for suggestions, on how to accomplish this.  While taking the picture, i decided to turn it upside down and see if it made a difference.  It sure did.

Does anyone agree with me?   This would make the job much easier, simply put the hanging sleeve on the other end, and somehow eradicate my signature, which is now upside down on the upper left corner.  I may still darken that narrow line a little but can probably accomplish that  with coloured pencil.

 With finishing this, I have been working on the charity quilt that started the whole thing.  Yesterday, I realized that I was getting a little tired of blue, especially when I realized that my  clothing for the past few days has also been blue.  So I am now doing the ground work ( dyeing at this point) on a new project which will be based on yellow, and today I chose to wear red.