A little more steps back

Until now, the best result I got was with the recipe below:

1 tsp washing soda

4 tsp soluble coffee

10 drops of lemon juice

10 ml CD4 5% solution

Water to make 500 ml
20 minutes development time and 40 ºC temperature

The photo you see below was an experiment to see what happens if we increase the coffee portion in the mixture. I made 30 minutes development because I already observed that there is no over-development but under-development may occur.

More coffee leads to loss of color

The result was not better, I got a darker negative but with less color.
So, by now, the above recipe is the best one.
Meanwhile I am testing some homemade recipes for the bleach-fix bath, because the bleach by-pass is not giving good results.
To be continued...