Purge ABS when swtiching to PLA

I switched from black ABS to orange PLA. Now I know it's a little challenging because the ABS is higher temp and the PLA is somewhat transluscent, but I've run probably a meter and a half of PLA through and I still get the occasional black streak.
I even tried upping the temp to the ABS extrusion temp and extruding a slug of PLA.

What's the best purging practice?

From ABS to PLA I do the following,,,

Set temp to 230C
Extrude about 20mm of ABS then immediately reverse 200mm to extract the filament.
Instal the PLA filament then extrude around 300mm before lowering the temp to 185C

---

_______________________________________
Waitaki 3D Printer

This is my method.

Start cold.

Set temp to 230C or about for ABS.

As the temp passes 170C apply upwards pressure on the filament. Usually pulling gently on the filament with one hand and gently turning the gear with the other.

Somewhere between 170C and 200C the ABS will let go of the extruder and come out cleanly. If done right you will see a short smooth section on the end.

Now feed in your PLA and push out a small amount to clear the nozzle.

Adjust temp down and you should be good to go.

Note: This works for J-head an EckerTech heads. Haven't tried any others yet.

---

Komb'
Glankonian Protoforms