The Rock Tumblers…

An internet search for rock tumblers took me to the website of Rotorua Lapidary who advertised that they sold rock tumblers. So I drove over there one day and bought three machines – two Lortone Model 33B Tumblers (each of which has two 3-pound rubber barrels) and one  Lortone Model 45C Tumbler (which has a 4-pound barrel). 

Two Lortone 33B Tumblers (with two 3-lb barrels each)
A Lortone 45C Tumbler (with one 4-lb barrel)

I had to guess what might turn out to be appropriate for us – I thought that Petra and I could each keep one of the 33B tumblers busy, and there is the flexibility of the two barrels – and we could share the larger one. Each 3-pound barrel is about 10 cms deep and 10 cms in diameter. The 4-pound barrel is 9 cms deep and 15 cms in diameter. The “pounds” refer to the weight of the load of stones that can be placed in them – three pounds is 1.33 kgs and four pounds is 1.8 kgs.

Three 3-lb barrels


The 4lb barrel

Colin Simmons of Rotorua Lapidary told me that he started rock tumbling in 1966. He opened his shop in Rotorua in 1981 and runs it with his wife Bev. He happily spent a long time with me, answering my questions about rock tumbling and offering advice based on his extensive experience. I am very grateful for the help he provided. Along with the tumblers I bought three grades of silicon carbide grit (100, 220 and 320), tin oxide polish powder (two grades – the “pre-polish” and the “pro-polish”), and plastic pellets (which are used to cushion the tumbling stones once they get more rounded or to make up a load if there’s not enough stones for the barrel). I was now ready to set up a small stone tumbling operation!

Beach Stones, The Raw Material

Beach stones are great for the tumble polisher. Compared to stones found in the ground, and in streams and rivers, beach stones tend to be rounder and smoother, and so are easier to polish. When wet, as they often are, their colours and patterns are clearly to be seen. On beaches with stones, there is usually a great diversity of types of stones within a relatively small area, minimising the time and effort when collecting them. 

At the beginning…

In February of 2016, my wife Petra and I were on holiday in the South Island of New Zealand. We had driven our own car down, crossing Cook Strait on a ferry, making our way to Golden Bay then south to Westport, down the West Coast then over Haast Pass to Te Anau and Riverton, right at the bottom of the South Island. Then we headed back north, driving up the eastern coast of the South Island, through Christchurch and Kaikoura then to Picton where we caught the ferry back to the North Island and a six hour car-ride home.

Somewhere between the West Coast and Riverton, we decided we would find out more about polishing stones. We have both always been the type who have walked beaches with our heads down, looking for interesting shells, driftwood and stones. The shells and driftwood usually found a place in the house or in the garden, but the stones that we collected have always been a problem. They just don’t look the same when they’re not wet. They tend soon to be overlooked or lost. 

I have an aunt who many years ago used to polish stones from Riverton – my grandparents had a holiday home (“crib”, in local terms) there, at Hendersons Bay, and my family usually spent a couple of weeks there every summer. 

Hendersons Bay, Riverton, where my family used to holiday when I was growing up.
Riverton topo 2
Hendersons Bay is towards the southern end of the Rocks Highway at Riverton. Source:

I remember the polished stones of my aunt, collected from Riverton – I never knew how she polished them but I was impressed with the results. Petra and I decided to collect some stones on our holiday and try to polish them when we got back home. We ended up collecting more and more stones as we went along,  weighing the car down significantly.

Upon arriving home, Petra and I did some internet searching and found out about rock tumblers. We bought three and started out on a journey of learning, of experimentation and of rearranging aspects of our domestic space to make room for it all.

This Blog is a way for me to share our discoveries, to share information, and to help others who start on the same journey. I can be contacted at – all comments and questions welcomed.