I was looking for methods to avoid the use of heating and mixing at the same time, using solid gold and I found this that it could be interesting for who uses gold chloride... Unlucky I can only use solid gold, but it could be a good idea if someone of you want experiment.
Good luck
https://nanoscalereslett.springeropen.com/articles/10.1186/1556-276X-7-420They made it with a jewellery cleaner.