Failing to get a Contact Dye Oak Leaf Print

"One of those weeks, isn't it, Beaut?"  Elinor Gotland may be a hard-hitting ewe, but even a stone would be moved to sympathy by the sight of my mangled knitting.
"That bloody puppy!  It's not just the wool and the work, she's chewed up the cord on my circular needle."
"I'd put that collar back on her."
Oh.  For reasons unfathomable to me, Yarrow went into a deep decline when obliged to wear a collar.  Not naughty, just miserable, for several days she had to be towed around on her lead or she would just lay down.
"All that rolling around whimpering and scratching at her neck, she only did that when you were looking."
"She's not an actress, Elinor.  I think the collar just made her very unhappy."  
My companion passed me a cup of tea and shoved the ashtray across.
"I don't know who's the bigger fool, you or that dog."

It was true enough, things have not been going to plan lately.  The falling leaves reminded me that last autumn, I got some nice oak leaf prints on silk and cotton, simply by rolling the fabric covered in leaves round a piece of plastic drainpipe and simmering it in leftover plant dye baths.  During my abortive attempts to walk the dog, I had been picking up fallen oak leaves and following the same procedure when we got home.

There were two plant dye afterbaths sitting on the patio, one still with a bag of dyers chamomile flowers in it and one made from yarrow and Achillea Coronation Gold, which contained a fair amount of iron as well as the blackened plant remains.  I soaked the string in iron water before tying the bundle for the chamomile dye bath and just put the other bundle straight

into the iron rich pot.  They looked much the same while drying out for a day or two.  I unwrapped them, curious to see if more iron made better prints only to find the oak leaves had hardly made any mark at all.  Last year, there were clear outlines and brown colours from the back of the leaves.  This time, if I hadn't included some dessicated stalks of coreopsis, which it turns out still make good orange prints even at the very far

end of their season, the scarves would have turned out utterly dull.
With the little dog's collar off, joyful racing about on walks resumed, though no obedient returning to my call.  Last month, training was going so well.  I am doing things wrong, but can't work out exactly what.  During a pause to catch my breath, curse my ignorance and folly and of course, the vagaries of an unkind world, I sat down on the deep red, prickly leaves of low growing brambles. 

Picking out the barbs, it occurred to me to try a contact dye with them in the same dye bath, maybe find out if the problem lay in the oak leaves or the dyebaths. In case it was insufficient iron, I rolled some rusty nails and washers into the bundle and as insurance, I added in sprigs of fresh coreopsis.  The plants had just been knocked flat by my lovely canine assistant, during another disagreement about who was allowed to dig the

garden and where.  Much better leaf prints appeared on the outer layer of silk, not so good on the deeper layers, despite dark stains of iron around the nails. 
Elinor and I sat on the patio, looking at the washed and ironed scarves hung out for display on the washing line.  We drank our tea and lit up.
"I think possibly those oak leaves I picked up were too dried out. Could try dyeing with some that have a bit of life and leatheriness left in them.  See what happens."
"Reasons to be cheerful, Beaut.  It isn't raining, your silk wasn't totally wasted and at least that dog is keeping you fit."