I recommend the white ceramic mechanical pencil for dark fabrics. It makes a vine line and is erasable. I also use the Multi-Pastel Chalk pencils in white or light grey. I have also been using the dark gray. For any of the chalk type pencils I recommend erasing first or at least wipe the lines with a terry cloth to remove any of the surface chalk. Chalk will cake in water unless the surface residue is removed. The cermanic mechanical is a bit pricy but leads go a long way and they are stronger than one might think. Pounce chalk doesn't stick to the fabric so will come off in the quilting and for me makes a white mess. Mairacle Chalk with the pounce pad works good It is removed either by brushing, washing or will come off it gently steamed off. I don't recommend any pencil that is color as sometimes the color does not come off.
I use a variety of marking pencils depending on the color of the fabric I am marking. I am having good sucess with the ceramic lead on black batik.
And as you have discoveed.........always test first.
You may need to spray with stain remover such as Shout before washing. I marked some light fabric with the dark mult=pastel and had to spray the lines.
There is also another pencil - Sketch and Wash that is a washable graphite. It looks deadly but I marked off white cotton sateen with it and it was almost gone by the time I finished machine quilting it and the rest ame off by erasing. All these pencils can be found in most LQS or the Multi-Pastel is an art pencil so might be found in an art suppky store as it is an art pencil. If you use the merical pounce you just rub it over the stencil like you would erase chalk from a blackboard. Don't pound it.