A test with x-rays

My cyanopés require a very long exposure time, at least 3 hours, but photo paper is much less transparent than normal photo negatives. But I don't have any negative film... What should I do? What if I tried with old medical x-rays? It's a negative on film, it could work, I'm testing it.

These are not my own x-rays, so I have blurred the patient's name to not reveal private medical data.

The exposure lasted barely two hours under overcast skies but it's only a first attempt, it could probably be much shortened.

I was very impressed by these cyanotypes, very sharp, very clean and ultimately very educational. I'm going to look for other x-rays for other tests, I'm looking for a skull x-ray, it should give a very interesting cyanotype.

Do you have x-rays and want to see them positively? You know what you have to do.