Currently, I am tumbling stones sourced from Hampden Beach, located just a short distance away from the renowned Moeraki Boulders and approximately a 30-minute drive from Oamaru. This proximity made it an ideal stop to gather more stones for tumbling on my journey back home.
The stones found in this area are likely sedimentary in nature. Sedimentary rocks form through the accumulation and compaction of minerals or organic materials, such as sand or mud, giving rise to varieties like sandstones and breccias. In contrast to the smoother stones at Kakanui, the stones I collected are notably rougher, necessitating multiple repetitions of Stage 1.
Indeed, my expectations were accurate as the initial Stage 1 tumbling process stretched on for 14 days. Given the stones’ battered condition, I observed some leakage around the lid and noted the barrel’s elevated temperature, attributable to the presence of borax. Subsequently, 17 smaller stones progressed to the 220-grit stage, while the remaining stones underwent another round of Stage 1.
To diversify the mix and address the distinct characteristics of the stones, slices from Gemstone Beach and Papatotara Coast were introduced into the second tumble at 80/100 grit. This stage also marked my debut with a wet tile saw acquired from Mitre 10, allowing me to experiment with slicing larger stones. The upcoming tumbling sessions will reveal how these stones fare in the process. Additionally, new ceramic pellets were added to this second Stage 1 tumble to facilitate the smoothing of any rough edges present on the stones.
Batch 49: 4lb Tumbler 1
Stage 1: 80/100grit
Number of Stones: 46
Weight in: 1032g
7 Tbspns of 80/100grit
2 Tbspn Borax
No pellets added
Days Tumbling: 14
Weight out: 700g – loss of 332grams!
Stage 1 (x2): 80/100grit
Number of Stones: 46+16-17=45
Weight in: 1211g
7 Tbspns of 80/100grit
2 Tbspn Borax
Ceramic media added
Days Tumbling: 12
Weight out: 977g – loss of 234grams
Observations:
After one tumble at 80/100grit the slices are looking rounded and smooth. The Hampden Beach stones are still quite rough. There was also a few chips in the barrel but that was expected. The “readies” were taken out and placed with the others for Stage 2.
Batch 49: Pre-tumble
Added to Stage 1 (2x)
Stage 1 (x3): 80/100grit
Number of Stones: 21+24=45
Weight in: 1032g
7 Tbspns of 80/100grit
2 Tbspn Borax
No pellets added
Days Tumbling: 14
Weight out: 700g – loss of 332grams!
Stage 1 (x2): 80/100grit
Number of Stones: 46+16-17=45
Weight in: 1211g
7 Tbspns of 80/100grit
2 Tbspn Borax
Ceramic media added
Days Tumbling: 12
Weight out: 977g – loss of 234grams
Observations:
After one tumble at 80/100grit the slices are looking rounded and smooth. The Hampden Beach stones are still quite rough. There was also a few chips in the barrel but that was expected.
Batch 49: After Stage 1 (3x)
Adding back for Stage 2
Stage 1 (x3): 80/100grit
Number of Stones: 21+24=45
Weight in: Forgot to weigh
7 Tbspns of 80/100grit
2 Tbspn Borax
Plastic pellets added
Days Tumbling: 10
Weight out: 897grams
Stage 2: 220grit
Number of Stones: 28+24=52
Weight in: 1055g
7 Tbspns of 220grit
2 Tbspn Borax
Plastic pellets added
Days Tumbling: 11
Weight out: 859g – loss of 196grams
Stage 3: 400grit
Number of Stones: 52+13=65
Weight in: 1000grams
7 Tbspns of 400grit
2 Tbspn Borax
Plastic pellets added
Days Tumbling: 9
Weight out: 828g – loss of 172grams
13 stones (redos from Gemstone Beach) were added to Stage 3 to help make up the load.
To help make up the load in the 4lb barrel Batch 51 (48 stones) was added to the stones going through to polish from Batch 49. A number of stones in both batches have pits or grooves but they are mostly shallow so will need to be inspected closely after this tumble.
I had to burp the barrel (first time I’ve had to do that) as there was a bulge on the bottom. I think the borax makes the slurry quite warm which causes the bulge.
Stage 4: 600grit
Number of Stones: 62+48=110
Weight in: 826g+430g=1256grams
7 Tbspns of 600grit
1½ Tbspns Borax
Plastic pellets added
Days Tumbling: 10
Weight out: 1109g – loss of 147grams
24 hour soap tumble prior to polishing.
In the end only 12 (Gemstone Beach slices) + 46 (Kakanui/Hampden Beach) stones went through to polish. The rest with withdrawn completely or put in the Kakanui redo box (17 stones – 236grams).
The stones on the right will not polish because they have bruises, pits, or lack the necessary smoothness for polishing. Many of them will not undergo tumbling anymore due to being too small to proceed or having pits too deep to be tumbled out.
Combined with this batch was 44 stones (Batch 51, Batch 52 from 3lbT4, Gemstone Beach) and 38 stones (Batch 53 from 3lbT3, Gemstone Beach).
Stage 5: Tumble Polish Mix
Number of Stones: 12+46+38+44=140
Weight in: 1991grams
Polish Mix (NEW): 9 Tbspns of polish mixed with 600mls of clean water.
Plastic Pellets added.
Days Tumbling: 11
Polish Complete
Batch 49 | 4lb Tumbler 1 | Hampden Beach (Gemstone/Papatotara) | 19 January – 7 April 2024
(Included Batch 51, 52 & Batch 53 at the polish stage – stones from Kakanui and Gemstone Beach)