I’ve been looking for a coarser grit than 80/100grit for a while now so I messaged the friendly, helpful peeps over at Rock and Gemstone Shop in Rotorua and asked if they had anything coarser. Turns out they do and it’s now available on their website to purchase! It’s 46 grit and I’m hoping that it does the job of smoothing out those rougher stones that are often found on Papatotara Beach just out in front of us.
Batch 35: 3lb Tumbler 3
Pre-Stage 1: 46grit
Number of Stones: 29
Weight in: 843g
4 Tbspns of 46grit – no pellets added
Days Tumbling: 7
Weight out: 750grams – loss of 93grams
Stage 1: 80/100grit
Number of Stones: 28+4+3
(added 4 kakanui stones & 3 Pap stones from redo box)
Weight in: 871 grams
4 Tbspns of 80/100grit – no pellets
1 Tbspn of borax
Days Tumbling: 10
Weight out: 750 grams – loss of 121 grams
Stage 1 – 2nd time: 80/100grit
Number of Stones: 35+16=51
Weight in: 750 + 157 = 907 grams
4 Tbspns of 400grit – no pellets
1 Tbspn of borax
Days Tumbling: 10
Weight out: 791 grams – loss of 116 grams
Batch 35: Pre-tumble
Batch 35: After 46grit
After 7 days in the 46grit the stones only lost approximately 93g which is a lot less than most of the other batches I’ve done starting in 80/100grit. Generally speaking most Stage 1 tumbles experience a loss anywhere between 100g to 157g. Only one stone didn’t make it through to the 80/100grit out of the batch – overall I was quite happy with just how much smoother the stones were before going into the official Stage 1.
As it turns out most of the stones in this batch continued to have grooves or pits that just wouldn’t smooth out. I decided to try tumbling them again in a new batch of 80/100grit (3rd time’s a charm they say!) I’m adding various Papatotara Stones each time to help keep the load barrel full even though this often makes tracking the entire batch quite difficult!
I have been adding a tablespoon of borax to the 80/100grit as well. Many of the rock tumblers that I follow do this so I’m curious to see if it makes any kind of difference. What I have noticed is that it does make the grit more “sludgy”. The reasoning behind adding a tablespoon of borax to your coarse grit is that it thickens the grit and that helps to carry the grit around the stones better.
I am making a conscious effort stick to the ⅔ rule of barrel filling. I’ve marked an acrylic stick and use it to mark the inside of my barrel with chalk before filling up the barrel with stones. I’m doing this because I think one of the reasons I’ve been having so much trouble with “pitted” stones is either overfilling or underfilling the barrel.
Stage 1 – 3rd time: 80/100grit
Number of Stones: 51+3=54
Weight in: 791+28= 819 grams
4 Tbspns of 400grit – no pellets
1 Tbspn of borax
Days Tumbling: 7
Weight out: 691 grams – loss of 128 grams
Stage 2: 220grit
Number of Stones: 54
Weight in: 619 grams
4 Tbspns of 400grit – pellets added
1 Tbspn of borax
Days Tumbling: 10
Weight out: 587 grams – loss of 104 grams
Batch 35: After 220grit
Those six stones I was watching smoothed out a lot but three of them not quite enough. (Two stones were removed from the batch for a redo at 220grit and one was removed completely – out to the garden pots.) Also removed one other stone because of bruising but will put it in the holding box for a redo at 220grit to see if bruising can be removed. Unfortunately there’s not enough Papatotara stones to make a full load for Stage 3 so these stones are “holding”
Transfer to 3lb Tumbler 4
3lb Tumbler 4 became free (because there was not enough stones in Batch 40 to carry on through with a polish tumble!) I’ve snaffled it to keep grit tumbling this batch plus a few more stones from the redo box (redos originally from batches 30, 34, 37). I do try to keep the stones grouped in the places that they are from but I wanted to get Batch 35 done and there just isn’t any Papatotara stones coming through in the other barrels plus there’s none sitting in the redo boxes for Papatotara either. So although these 13 “redo” stones are mostly from Kakanui with a couple from Gemstone Beach – the majority of this batch is still Papatotara Coast stones.
Stage 3: 400grit
Number of Stones: 50 + 13 = 63
Weight in: I forgot to weigh!
4 Tbspns of 400grit – pellets
Days Tumbling: 10
Weight out: 576g (as I forgot to weigh in, I don’t know how much volume the stones have lost in this cycle.
There were a lot of stones not ready for polish. Out of the 63 (after taking out the Kakanui looking stones) only 29 stones were ready for polishing – placed these in the Polish Holding Box and labelled them Gemstone Beach stones (Batch 35) by accident. They are mainly Papatotara Coast stones.
Transfer back to 3lb Tumbler 3
All this mixing up, redos, changing tumblers etc has gotten so confusing!! Note to self – don’t do that again! Anyway, we’re back to 29 stones in the batch and they were finally added to a batch that was also ready for polishing. Batch 45 needed some help to make up the polishing barrel load. If you’ve managed to keep track of all the too-ing and fro-ing of this batch I congratulate you because I’m well and truly confuddled!
Stage 4: Polish Mix
Number of Stones: 29+58(Batch45)=87
Weight in: 729grams
Polish Mix (2nd use): 5 Tbspns of polish mixed with 300mls of clean water. Pellets added.
*Also added 1 Tbspn of borax (explained why in Batch 45’s post)
Days Tumbling: 10
Weight out: 726g – loss of: 3grams
Stage 5: Burnish
1½ Tbspns borax, pellets added.
Days Tumbling: 4
Polished Stones: Batch 35 & Batch 45
46 Grit – update
I have just read that 46grit IS NOT suitable for rubber tumbling barrels and is recommend for use in metal barrels/drums ONLY. Ooops!! Perhaps I’ll use it sparingly then?
Batch 35 | 3lb Tumbler 3, 3lb Tumbler 4 | Papatotara Coast stones | 13 October 2023- 29 February 2024