null24 sometimes, actually quite regularly stains appear that just won't shift with all the techniques you mentioned and even getting part of a choreboy/brillopad in thehole even when used for intended chemical, I always buy them by the half dozen as they break easily and get filthy so fast and can't be properly cleaned, by me anyway. I have that exact same pipe. It is slightly thicker than an average crack pipe so the technique requires refining. It takes slighty longer to heat up and cool down. I tried dmt freebase quite a few times in it I approached from as far away as I could reach with my lighter and approached until instead of vopourising started to burn (works great with crack though). All I got was the outside wall of hyperspace with it's back turned on me as a CEV.
A bit like "Frank" backgrounds in Jim Woodring graphic novels. Happened numerous times and was a clear message to me not to approach hyperspace via a £4.00 crack pipe.
And even worse the smiley face washes of when giving pipe a good scrub down.
Anyone more experienced want to jump in? I feel that which has not vapourised is now burnt and useless.
Glad you had moar success with it than I did and you did get a breakthrough which is denied to many so well done Clife777.
It is a matterof where on the globe you live in country ie were MHRB is legal or easily sourced or one of the places acacia grows wild.
So, if it is rare and unattainable make a big effort to recover any remnants.
good luck