In the previous section we talked a lot about properly loading the barrel and which cushioning media to use, so now it’s time to add water and grit in preparation of getting rolling. This information may seem a bit more obvious at first, but take it from the experts, it’s very important to get right. A properly wet barrel with the right amount of abrasive grit can literally be the difference between achieving a proper slurry coating and wasting a week only to discover a disappointing lack of coverage on your tumbling load.
What follows next in no specific order is a bullet list of pro-tips, tricks and advice on the subject of adding the right amount of water and grit to your tumbler barrel, contributed by the Rock Tumbling Hobby Forum community.
Add water first before adding abrasive grit to your properly loaded tumbler barrel full of rocks. If for no other reason, adding the water first allows you to pour some out if you accidentally overfill which is not so easy if you have already added grit and much of it has fallen down in the spaces between dry rocks.
Add only enough water so that you can see the water level emerge in between the top row of rocks in the barrel, and don’t let the water level completely cover the rocks.
Consult with a recipe specific to your barrel weight size and use it to guide you on how much grit to add to the barrel.
If you are not already, familiarizing yourself with the differences between Silicon Carbide (SiC) grit and Aluminum Oxide (AO) grit can be very helpful from a rock tumbling standpoint.
A trend has emerged in recent years where rock tumbler manufacturers and grit dealers want you to purchase rock tumblers and grit branded and sold as a kit, or refill kits, labeled with terminology such as Stage 1 through Stage 4.
Selling grit as a kit in equal sized packages does not make a lot of sense to experienced rock tumblers because we know that the course grind of hard stones almost always takes up to several times longer than the later stages do. Along the way you’ll stop and check the rocks at least a couple of times to see if they are shaped properly, and you will probably want to recharge the barrel with fresh grit and spritzes of water when you do.
We recommend that if the grit size is not clearly communicated on the package, set it aside and purchase grit in bulk (by the pound) with a known grit size, from a trusted source. Before you commit to a large bulk purchase of grit from a seller you have not developed trust with, it’s OK to ask for a sample or if you can purchase a sample of the product for testing. Not all grits are created equal.
Add your grit appropriate for the stage you are in and carefully seal the barrel making sure there is no grit or dirt on the lip. If debris are present on the lip of the barrel, scrape it thoroughly with a firm object like a credit card until it is clean and free of debris.
Filling the barrel with hot water before sealing can help offset some of the gas build up in the barrel and keep the lid on a bit better. Combine this trick with screwing the nut on a bit tighter than you might normally and are less likely to experience a blowout.
You can avoid leaks and potential blowouts by gently tapping around the lid with a rubber hammer or similar tool, making sure lid is seated firmly in place before you fasten the nut tightly; but not so tightly that inner lid is warped.
Shake and barrel from end to end and roll it around a few times to make sure the grit is dispersed in the water throughout the tumbler and you should be ready to roll.
Now that you have thoughtfully added your grit and water and securely fastened the barrel lid, it’s time to move on to Part 5 of this series: Rotary Rock Tumbling – Get Rolling
