yeah, the mix of the 2 congeals like a jelly substance, everywhere. If you catch it quick you can push it out and rinse with alcohol. If its been awhile, disassemble and blow out the lines, disassemble the mc and calipers and clean. At that point, I would replace the seals also if your apart that far.

 

I could write a horror story that would scare Stephen King himself on mixing DOT 3 and 5. If you have mixed the two, buy a rebuild kit for the caliper and master cylinder, clean everything including the brake line with brake cleaner, then commence with the rebuild.