I just did a rather ugly batch with my homemade dextrine - it turned purple alright, but then stayed at a redbrown stage.
On the other hand, 10 minutes after that I made my best colloidal gold ever - it really looked the business! I've made six batches colloidal gold in total right now using the maltodextrine and dextrine formula.
In chronological order:
1. Maltodextrine 125 mg - amethyst.
2. Maltodextrine 125 mg - amethyst.
3. Maltodextrine 250 mg - grey.
4. Maltodextrine 60 mg + 60 mg at the end - deep ruby red with a slight blue hint.
5. Invert sugar+Dextrine 300 mg - redbrown.
6. Maltodextrine 60 mg, premixed with Na2CO3 in DW, added when boiling - beautiful crystal clear red.
The reason for my failures seems to be due to three factors:
1. My maltodextrine has more reducing power than the one Kephra uses.
2. I had too low temperature in my first three batches (not having flat glassware on my heating plate).
3. Speed - when I got to adding the Na2CO3 in batch 3, it had already turned a dark purple with ONLY the maltodextrine.
Making colloidal gold seems more "artistic" than making colloidal silver
.
/J