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aplomado

Anyone use 1/8" mesh in a sifter?

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aplomado

All the rest of our sifters use 1/4 mesh (for sifting in creeks).  Does anyone used one with 1/8 mesh for catching tiny stuff?  How does it work?

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hadrosauridae

If you do, you need to stack sifting screens or youre going to have giant pile of debris and you still wont be able to see anything tiny.  I'd recommend a 1", 1/2" then 1/4", then you can more easily and thoroughly search each one in a few seconds.

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jpc

with a layer of window screen on the bottom...

 

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digit

Indeed. This seems to be the tried and true method. The larger (in this case) 1/4" screen will remove the larger pieces (which can be searched easily in the field for visible fossils). The window screen allows some of the finer sands and sediments to be left behind in the field. This would be effective on a land site with dry matrix but does not work so well if the matrix is damp as very little will pass through the window screen. In a river or creek (or lake) you can use water to aid the sifting process and flush out quite a bit of fine sediments before taking home the fine matrix.

 

I documented the process I use a while back and it may prove useful here:

 

http://www.thefossilforum.com/index.php?/topic/51286-collecting-cookiecutter-shark-micro-matrix/

 

I have a set of stacked round sifters that are sized to fit over the top of a 5-gallon bucket (purchased online). I've occasionally taken a few of these out in the field if I want to collect a particular size class that is between the two mesh sizes that I stack together but usually I just use two screens with 1/4" mesh in the top one and a loose piece of window screen in the bottom one. After drying at home (on a tarp in the driveway) I run the bulk micro-matrix through my stack of sifters to classify it into various sizes to assist in picking.

 

Cheers.

 

-Ken

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aplomado

Thank  you!  I am now thinking about a double decker sifter.

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digit

Using stacked sifters to delimit a chosen size range of gravel/matrix is very effective. Use a wider range in the field while collecting (1/4" and window screen mesh are my default) and then classify the collected material back home with a stack of sifting screens to optimize searching the material.

 

 

Cheers.

 

-Ken

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aplomado

Planning to try and construct a double decker sifter tonight...

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digit

Take photos to document your process and post it here as it could be informative to others attempting to do the same. ;)

 

 

Cheers.

 

-Ken

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T. nepaeolicus

Why would you want to catch the tiny stuff?

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digit

How else would you find tiny treasures like this commissural tooth from the Cookiecutter Shark Isistius triangulus that is not quite 2 mm long? ;)

 

2020-01-04 09-57-42.jpg

 

Using a fine screen mesh in the bottom sifting screen keeps you from taking home the mostly unfossiliferous finest sand and silt while still holding back unusual specimens like this. Picking micro-matrix is not for everyone. It takes a lot of patience (and some special equipment) to spot micro fossils which are rarely impressive looking without magnification. For those of us who are hooked on doing our fossil hunts from the comfort of a cushy chair in a temperature controlled environment, there is nothing else quite like it. :)

 

 

Cheers.

 

-Ken

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grandpa
26 minutes ago, T. nepaeolicus said:

Why would you want to catch the tiny stuff

Because there is much, much overlooked science lurking in the "tiny stuff".  Oh yea, and because finding that "tiny stuff" is a real hoot!  :D  :egypt:

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hadrosauridae
On 5/15/2020 at 10:50 AM, aplomado said:

Planning to try and construct a double decker sifter tonight...

If you arent happy with your result, look up the Keene gold prospecting classifying sieves.  They are stack-able, fit into most 5 gal buckets, and available from 2 mesh to 100 mesh screens.

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digit
7 minutes ago, hadrosauridae said:

If you arent happy with your result, look up the Keene gold prospecting classifying sieves.  They are stack-able, fit into most 5 gal buckets, and available from 2 mesh to 100 mesh screens.

I have these as well and use them to classify the micro-matrix after collection. I've used them in the field on occasion like when I wanted to collect down to 1/30" or 1/50" matrix (finer than I get with a piece of window screen in the bottom sifter). Usually though I just use two of my floating sifters that I use while hunting for larger fossil in the Peace River. Those screens have enough "pool noodles" attached to give the screens good buoyancy and I can stack two of them easily with a loose piece of window screen in the bottom siifting screen. When I've removed the 1/4" mesh screen I use in the top sifter I can easily pick up the large square of window screen mesh and by grabbing it with two corners in each hand I can roll around the fine matrix while dunking it in the water which flushes out a lot of the fine sand and sediment. I can then carry it to my awaiting 5-gallon bucket and by letting go of one side of the screen easily dump the load into my bucket. Doesn't take long to fill up a bucket if you've got a gravel bed with lots of fine material in it.

 

I've stacked a 1/4" and 1/30" round green plastic sieves and shoveled material into them but I either need someone to hold them (as they don't float) or set them on the bank while filling. They are smaller than my 16" x 16" sifters and so it takes longer to fill a bucket. If I want to collect finer than my window screen will allow I find them useful, otherwise I stick to my stacked sifters and loose piece of window screen--simple and reuses my "normal" sifters so all I have to take extra if I want to collect micro-matrix as well as larger fossils is the piece of window screen (and, of course, a bucket for the matrix).

 

 

Cheers.

 

-Ken

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aplomado

The good news is the double decker sifter worked really well...


The bad news is I realized how many fossil have been losing through the 1/4 screen!

 

Most of the teeth actually ended up in the 1/8" mesh screen.

 

I will post a picture of the sifter later.

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digit

There are always more small teeth than large ones. Some species like Cookiecutter Sharks, Rhizoprionodon (Sharpnose Sharks), and Mustelus (Smooth-hound Sharks) have tiny teeth that would always fall through a 1/4" screen. You won't be finding any megs (not even baby ones) but you'll start seeing a new world of mini fossils. ;)

 

 

Cheers.

 

-Ken

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aplomado

Ok, here's our first double decker sifter (thanks for the idea hokietech96!)... it worked so well Saturday I made another today.  Instead of a hinge holding the sifters together, I attached the two with a pair of draw hasps I got at lowes (Gatehouse brand,  2  3/4 in), one on each side.  They can be completely separated for sorting, as you can see.

 

The top has 1/4 in mesh.  I covered the wire edges on it with metal edging made for drywall corners.

The bottom has 1/8 inch mesh.  I covered the edges with wood trim.  Both work well.

 

Most of the good fossils ended up in the bottom screen!  The best find of the day for me was a partial (crab?) claw that I picked out of the 1/8 screen.

 

The only negative I can see about this setup is that it is kind of heavy.  Using a narrower board for the top screen might be a good idea (the top is about 2.5", the bottom is about 1.25" wide)

 

5ec1e085c384f_doubledecker2.jpg.56646030b688eac5b61d71326a7b6d4c.jpg5ec1e0761b2b5_doubledecker1.thumb.jpg.39a81453f84090cd56db90e7757a2590.jpg

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digit

Looking good. Waiting to see photos of the micros. They can be a real pain to photograph. ;)

 

 

Cheers.

 

-Ken

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hadrosauridae

looks really good!  Yes, solid wood is heavy but I promise that what you built will last a LOOOONG time.

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