Why aren't my tumbled stones turning out shiny or glossy?

Your stones are finishing the polish stage in your rock tumbler.  You excitedly take them out, rinse them off dry them, and....they aren't glossy.  They aren't shiny.  They are...disappointing.  Especially because it took weeks to get to this point and you even followed the directions that came with the rock tumbler exactly! 

Why aren't the rocks turning out shiny or glossy?

The first and likely biggest culprit might just be that you followed the directions that came with your rock tumbler, used the stones that came with in the kit, and also used the grit packets they send along.  I haven't read the directions that come with every tumbler starter set out there, but I have read several, and to put it mildly...they are misleading.  

Those starter sets?  They come with stones that shouldn't be tumbled together (and won't turn out well if you do).  The grit packets they send along?  The first couple are usually okay, but the pre-polish and polish packets are typically low quality and don't give good results.  The directions make it sound like 3-5 days per stage are fine, just crank up the speed!  But that's not how rock tumbling works.  Faster is not better.  Slow and steady nearly always wins the race.  

So what are the lessons to be learned from that?

One, separate out the stones by hardness.  Sodalite should not be tumbled with jaspers.  Tiger's eye might polish okay with agates and jasper, but it's also likely to bruise.  It is easiest to begin rock tumbling with stones of known hardness.  Starting with and agate, jasper, aventurine, or quartz mix is your best bet since they are mixes with similar hardness.  The mix shown on the right includes stones of different Mohs hardnesses. Unakite (6-7), fluorite (4), prehnnite (6-6.5), labradorite and moonstone (6-6.5), quartz (7), obsidian (5-5.5), amazonite (6-6.5), sodalite and rhodonite (5.5-6), and jasper (7) have varying hardnesses and if tumbled together, would give subpar results.  Only stones of similar hardness should be combined, and even then, tumbling materials of the same type tend to give the absolute best results.

Two, buy a quality grit starter pack.  We like to use Rock Shed or Kingsley North for grit, both have comparable pricing and quality.

Three, tumble the stones on stage one for multiple weeks, changing out the grit weekly and taking out stones that are well rounded/shaped, replacing with stones that are new.  Then do subsequent stages for one week.  Always use the slowest setting on your tumbler if it has speed control.  Faster speeds are necessarily going to make them shape faster, but they are more likely to bruise, chip, or become damaged.

What are some other reasons your stones aren't turning out?

• Improper grit washout:  If you aren't rinsing the stones AND the barrel/lid thoroughly, grit will be carried over from one stage to another.  It's also more likely to have grit carryover if your stones are not well rounded and smooth.  Stones that have fractures and pits are likely to have grit and slurry compacted in those areas.  See our blog post about cleaning stones between stages.

Pitted and fractured stones like this petrified wood (above) can hide grit and slurry, making it harder to prevent contamination in later steps.  Meanwhile, well rounded stones like the red jasper below, are easier to clean between stages.

• Not removing chipped or damaged stones.  A chipped stone in anything stage 2 (220 grit) and beyond can scratch up and damage other stones and should always be removed.  The volume can be replaced with tumbling media to maintain the correct barrel volume.

   Chipped stones like this sodalite (left) can ruin an entire batch of stones and should be removed as soon as found.

• Not utilizing media as a cushion, or using media improperly.  Using media can help reduce bruising and chipping by cushioning stones, and can also be a carrier of grit to tight crevices and areas of the stone not likely to come into contact with other rocks during the tumbling process.  But it needs to be used correctly.  Plastic media needs to be kept separate for each stage.  Plastic pellets you used for 220 grit stage cannot be moved on to 500 grit stages because the grit can cling to the plastic making it difficult to make sure there is no carryover.  Ceramic media can move between stages, making it easier to work with.  For some stone material, you need to have a higher media to stone ratio to properly tumble the stones.

Going through weeks of rock tumbling to only get an end result that is lackluster can be extremely frustrating, and even cause many people to give up before they attain any level of success.  Most of the issues creating dull stones are easy to fix, as long as you have enough patience to try again!