goldfinger1
starting to spend too much on rocks
Member since November 2008
Posts: 154
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Post by goldfinger1 on Jul 24, 2021 6:54:09 GMT -5
Am looking for someone with a flat lap that would polish some slabs for a fee.
They are nice agate slabs that came from Idaho. Will not arrive until mid August. Just checking around now to see if anyone might be interested.
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goldfinger1
starting to spend too much on rocks
Member since November 2008
Posts: 154
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Post by goldfinger1 on Jul 24, 2021 18:05:03 GMT -5
You don't necessarily have to use a flat lap. I just think it would be easier and less prone to breakage.
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Post by jasoninsd on Jul 24, 2021 20:12:03 GMT -5
Out of curiosity, would they be able to be polished in a vibe as opposed to flat lap?
Or are you looking at strictly doing a one-sided face polish on the slabs?
What size are the slabs?
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goldfinger1
starting to spend too much on rocks
Member since November 2008
Posts: 154
|
Post by goldfinger1 on Jul 25, 2021 6:26:25 GMT -5
Out of curiosity, would they be able to be polished in a vibe as opposed to flat lap? Or are you looking at strictly doing a one-sided face polish on the slabs? What size are the slabs? I would prefer a one sided polish. These are seam agates and are in the 4 to 5 inch long range and 1.5 to 2 inches wide. Thickness is 4 to 8 mms. |
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Post by jasoninsd on Jul 25, 2021 12:14:36 GMT -5
Definitely the work for someone with a flat lap then!  |
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Post by greig on Jul 25, 2021 16:39:11 GMT -5
Definitely the work for someone with a flat lap then! Or somebody with various grits of wet automotive sandpaper, time and a strong arm. ;-) |
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Post by Rockindad on Jul 25, 2021 18:27:37 GMT -5
Definitely the work for someone with a flat lap then! Or somebody with various grits of wet automotive sandpaper, time and a strong arm. ;-) Have done the sandpaper trick plenty with my woodworking chisels, plane blades, etc. before I got a sharpener. Tried it on rocks when we started in the hobby to see if it would work. It does, and I did it just enough to know I don't want to do it anymore  . |
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goldfinger1
starting to spend too much on rocks
Member since November 2008
Posts: 154
|
Post by goldfinger1 on Jul 26, 2021 6:17:22 GMT -5
Or somebody with various grits of wet automotive sandpaper, time and a strong arm. ;-) Have done the sandpaper trick plenty with my woodworking chisels, plane blades, etc. before I got a sharpener. Tried it on rocks when we started in the hobby to see if it would work. It does, and I did it just enough to know I don't want to do it anymore . So these could be polished by hand? What materials would it need? |
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Post by Rockindad on Jul 26, 2021 9:38:50 GMT -5
Have done the sandpaper trick plenty with my woodworking chisels, plane blades, etc. before I got a sharpener. Tried it on rocks when we started in the hobby to see if it would work. It does, and I did it just enough to know I don't want to do it anymore . So these could be polished by hand? What materials would it need? We used various grits of wet/dry sandpaper lightly wetted up to I believe 3000. After that we used Aluminum Oxide on damp denim from an old pair of jeans. Most important is that you have two very flat surfaces- the cuts on the material and the backing for the sandpaper, we ended up using a piece of plate glass we picked up from a local shop. We did four thunder egg halves and they turned out decent but not good enough that he wanted them for his own collection. They were good enough that he was able to sell them at a show he did. If these are truly slabs that you are going to polish only one side you might want to glue a block of wood to the unfinished side to give you something to hang on to. Have also read about people using of SiC powder on a wetted flat surface, have not tried it myself though. Do not recall how they ended up doing the final polish. |
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Post by greig on Jul 26, 2021 11:01:49 GMT -5
Sandpaper works fine if you work at it. It is best if wet, so I usually dip my rock and sandpaper often to keep them moist and clean (or spray with a fine mist). I use coarse automotive sandpaper to remove wheel marks and then quickly work my way up from about 180 grit, 300, 400 to 600 or 800, removing scratches from the earlier grits. I will use 1000 and 1200 if I have them. Polish on most rocks starts at 1500 and I usually also do 2000 and 3000. I stop when I can no longer see a difference/improvement. I have sometimes gone to 5000 or 6000 grit.
The trick is to have an assortment of sandpapers. If you are only doing this once, then buy a variety pack. The more grits, the faster the job will be. I usually do at least 5 minutes per grit. With the finer polishing grits, just use the weight of the rock and don't push down.
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