fixfireleo
starting to shine!
Member since March 2014
Posts: 30
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Post by fixfireleo on Mar 23, 2014 15:35:20 GMT -5
I have some clam shells that i found in FL. they have ridges but arent too thin. what's the best way to polish them and will they end up with a "mother of pearl" type look similar to some shells that i have found that have been naturally tumbled by the sea? i have a rotary and vibrating tumbler. i figured the vibrating one would be best. i assume i will need to use some filler beads. i have tried to attach a photo but this is my first time so i dont know if i did it right. thanks in advance. the "insert image didnt seem to work. the link to photobucket is s108.photobucket.com/user/fixfireleo/media/IMG_0075.jpg.html
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Post by Peruano on Mar 23, 2014 16:16:17 GMT -5
Here's your photo - you should use the img link (the last of the options in the Photobucket list). How your shells fare will depend on several factors. If they are not too big for the vibe use it, and probably start at 200 grit. I have tumbled lots of already tumbled shells which had no thin, or sharp edges and they did fine, although they do wear down if you let them go too long. I'd go light on grit, use some filler and the right amount of water to soften the tumble, and check them every few hours. You may build up a putty-like slurry that if it gets too thick will clog up the action. If so rinse it out and start with a small amount of the next stage grit. (probably 24 hours per stage will be plenty). I hope this helps. The shells I've tumbled have had all of the ridges worn away before I started and hence I can't predict what you will arrive to starting with the fresh shell that you have. Here are some of the shell remnants that I have tumbled. Here's the structure underneath those ridge (at least on the shells I'm doing). I've highlighted the texture a bit with a rubbing of India Ink just to enhance contrast. Unfortunately the take up of ink is quite variable and patch on some shells. Good luck. Tom
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Mar 23, 2014 23:17:55 GMT -5
I've polished shells in a rotary. I filled two 12 lb barrels just as full as I could get. Charged with 120 /220 grit, filled 3/4 with water. Ran for one week. This gave me enough shells for a 12 lb with a bit left over. Moved straight to polish, used Titanium Dioxide and lots of plastic pellets, ran for a week, followed with a couple of days in soap.
Learned by trial and error to not do a rough grind -- won't grind the shells, just settles out and just gives more time for the shells to break. Also found that the 600 grit run was unnecessary and just greatly decreased yield.
The vibe also worked, but I wasn't as happy with the results -- probably because I don't have the ability to use different sized barrels with the vibe so I couldn't (didn't) do as good a job controlling volume. I have 12, 6, 4.5, and 3 lb Lortone barrels.
It's critical to fill the barrel just as full as you can with shells (I even shake to settle to get more in)- to the point that you'll think nothing can happen. If you fill to the same directions as for rocks all you do is break shells.
I have some pictures posted on this site of some shells I polished. I'm traveling and on a mobile device so I don't know how to get to those pictures -- search my posting history and you may find them
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Mar 24, 2014 5:18:15 GMT -5
Filling rotary barrels to 7/8 full has worked here too. Any soft or impact sensitive material is much safer in a full barrel.
The other extreme is under filling in coarse grind to knock sharp edges off of hard agates. An under filled barrel chips sharp edges off. Better to have chips and vulnerable spots removed during early stage of coarse grind. Works for hard agates and jaspers-not obsidian glass or shells.
An overly full barrel works well for polishing too.
The sound can tell you a lot.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Mar 24, 2014 5:50:04 GMT -5
I have some clam shells that i found in FL. they have ridges but arent too thin. Read more: forum.rocktumblinghobby.com/thread/64973/advise-on-shells?page=1&scrollTo=734831#ixzz2wsGOIbT9That clam shell is common on the NE florida coast fixfireleo. Picked up a bunch off the beaches of Amelia Island. I had no idea that it would tumble to such a cool pattern. Seen a lot of broken beach tumbled pieces of that clam too. Never realized it had a spectacular pattern as shown by your application of India ink. Marine animals can make some extreme patterns. You might venture into the salt marshes behind the barrier islands at low tide and try for some quahog clam shells. The ancients made wampum beads out of the purple section of the shell. It is a very thick shelled clam. Hear are some images of the quahog. If you dig live ones you can eat the meat too. And may get an elusive purple pearl out of the deal.
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,547
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Post by tkvancil on Mar 24, 2014 10:24:30 GMT -5
Glad this thread came up. Got a coffee can full of shells on my "to do someday" list.
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fixfireleo
starting to shine!
Member since March 2014
Posts: 30
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Post by fixfireleo on Mar 24, 2014 12:07:41 GMT -5
ok, so let me surmise...my shells are not very small. they are about the size of a computer mouse. (THANKS Peruano for getting that image up. i must have clicked the wrong link. the one i used asked for the URL but didnt seem to link anything.) now, i'm not sure which tumbler you guys are recommending, vibrating or rotary. (i have 12 pound rotary and 10 pound vib). with the shells being so big, i'm not sure how tightly i can pack them. should i use filler on the rough tumble too? if i have enough, should i do 2 rough batches then transfer all to the polish? or, with such large shells, should i just forget the idea? thanks for the input!
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Mar 24, 2014 18:13:05 GMT -5
Collect a bunch of smaller broken filler shells. I've done shells with both rotary and vibe successfully. I preferred the results from the rotary, but your mileage may differ.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Mar 24, 2014 20:47:25 GMT -5
Glad this thread came up. Got a coffee can full of shells on my "to do someday" list. dito
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Post by wireholic on Mar 25, 2014 15:08:37 GMT -5
Love the patterns on that shell! I've polished up abalone but never bothered to pick up the clam shells. Think I'll go to the beach this weekend
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mrbouldersmash
off to a rocking start
Member since March 2014
Posts: 12
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Post by mrbouldersmash on Mar 27, 2014 20:55:58 GMT -5
i've never tumbled shells before, but you could look out for some small craft beeds, they look a little like the plastic tumbling pellets you buy, i bet there half the price to. seed beeds are maybe too small at 1mm, crow beads to big at 5mm+, so inbetween say 3-4mm. but I shell leave it to sombody with experiance. I just think of the sea and how they polish naturaly, maybe seed beeds would work, make a braclett after your done tony
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