Min

If the colour is the same in both (I'm guessing it is if you haven't noticed a difference) then put a drop of water on a piece that was for sure bisqued to 1860F and time how long it takes to soak into the clay. Repeat with the clay that was possibly only bisqued to 1200F and see if takes longer. You can also stick your tongue on both pieces, the lower fired one will stick more. (maybe don't do this in public)

@NancyE, sorry for the late reply, I was away for a bit.
Since the beginning of this year I've had problems with 2 different claybodies from 2 different manufacturers. First issue was bits of metal in the clay which doesn't sound like your issue. Second problem was with a claybody that included small chunks of rock which sounds like it might be the same issue you are finding. This clay was from Tacoma Clay Art Center and the clay tech and I had several productive emails back and forth about it. Image below of a couple of the small chunks of rock I dug out of the clay. Is this similar to what you found?
Rae (clay tech at Tacoma Clay Art Center) and I both ran sieve tests on it and found chunks like this. Rae let me know they are having troubles with all their claybodies that contain Lincoln 60, to the point that they are running QC tests on all the new batches of it. She ran samples through a 60 mesh sieve and 4% of it didn't pass through. I would ask Aardvark if the Black Mountain contains Lincoln 60, might be a place to start.

Take your claybody that the pots are made with and run it through a 60 mesh screen to remove most of the grog / sand. Brush that onto the feet of the groggy clay pots. After glaze firing rub the foot over with a diamond sanding pad.

If the colour is the same in both (I'm guessing it is if you haven't noticed a difference) then put a drop of water on a piece that was for sure bisqued to 1860F and time how long it takes to soak into the clay. Repeat with the clay that was possibly only bisqued to 1200F and see if takes longer. You can also stick your tongue on both pieces, the lower fired one will stick more. (maybe don't do this in public)

If the colour is the same in both (I'm guessing it is if you haven't noticed a difference) then put a drop of water on a piece that was for sure bisqued to 1860F and time how long it takes to soak into the clay. Repeat with the clay that was possibly only bisqued to 1200F and see if takes longer. You can also stick your tongue on both pieces, the lower fired one will stick more. (maybe don't do this in public)

If the colour is the same in both (I'm guessing it is if you haven't noticed a difference) then put a drop of water on a piece that was for sure bisqued to 1860F and time how long it takes to soak into the clay. Repeat with the clay that was possibly only bisqued to 1200F and see if takes longer. You can also stick your tongue on both pieces, the lower fired one will stick more. (maybe don't do this in public)

Rutile is one of those materials that can make or break a glaze, it can vary a lot from batch to batch. I would try it out with a small test batch before using it in a large bucket of glaze. Colour difference might just be your new batch hasn't been calcined. 

Take your claybody that the pots are made with and run it through a 60 mesh screen to remove most of the grog / sand. Brush that onto the feet of the groggy clay pots. After glaze firing rub the foot over with a diamond sanding pad.

Xiem BatMate is used for different purposes than the neoprene disc. My neoprene disc is about 3 mm thick. I use a Xiem BatMate (or a knockoff of it) to hold batts to the wheelhead without using batt pins but not to trim on. I know a lot of people use the Xiem BatMate to stop  wobble in uneven batts with the use of pins but it works super well with plaster batts of any size and wood batts up to about 10" without pins at all. I use the neoprene only for trimming. Still have to keep a slight pressure on the top of smaller pots like mugs, no need for clay wodges to hold the pot down.

More reading:
Very paranoid about Silicosis - Studio Operations and Making Work - Ceramic Arts Daily Community
Silica Dust Exposure - Studio Operations and Making Work - Ceramic Arts Daily Community
Can air purifiers remove silica dust from my Ceramic Studio - Studio Operations and Making Work - Ceramic Arts Daily Community|
Dust Collection For Small Studio - Clay and Glaze Chemistry - Ceramic Arts Daily Community
Toxicity (digitalfire.com)
Dedicated Studio shoes/sandals, no tracking clay into the house!
For if/when clay gets on clothes, have a few clean sets handy in the Studio.
Change rags when there's any dry clay on thar, bag or drown in water, along with dusty clothing! ...else, wet that rag.
Wipe down clay smear/bits inside the clay bags with a big ol' sponge, then spray a mist of water in thar before closing up the bag.
Dry clay on plastic sheeting/bags -> instant dust!
Handle the dried out empty clay bags outside, away from the Studio (clean inside and out, save for reclaim!).
Some forum regulars are using air filtration systems, also centralized vacuums (where the exhaust is routed outside/away).
My overhead kiln vent doubles as a glaze mixing station fan.
I'm handling the glaze material outside, away from the Studio door - repacking from the sacks and bags into lidded containers - then hosing the area down later.
Find a P100 (or equivalent) dust mask/respirator that fits you well and wear it when doing dust things.
Check/clean surfaces regularly. Note where dust accumulates, and how much - that's why I believe wedging and trimming are what generates dust in my Studio.
How else can one assess the dusty-ness of the working space?
Heh, I've posed this question several times over the last five years or so...

I originally stumbled across this forum while doing a Google search. I noticed fairly early on that when I did a Google search this forum came up quite frequently; often with multiple threads on the topic. I use the search function here less frequently now given it only searches threads that have been active for the past two years.
Don't know if this is an issue for others here? 

My suggestion for a QOTW came about from this thread. The thread drifted a little to include a members comment that cone 6 electric is easier than cone 10 gas reduction. My initial thought was yes firing an electric kiln is less time consuming than firing reduction but there are tradeoffs. 
I’ve always found cone 10 clay nicer to throw than any of the midrange clays I’ve used, the glazes (and clay) are generally less expensive to make for high fire and I also agree with what Michael Cardew said, electricity is a harsher judge of pots than reduction. I find that gifts from the kiln are far less frequent with electric firing vs reduction. Wood firing would top my list as the most work.
So, electric or gas reduction firing at any cone you choose, which is more work overall and at what stage of the pot making is it more work than the other? Also, is firing one way more enjoyable than the other?
And to make this into a 2’fer QOTW suggestion, another question would be this: hypothetically speaking if zoning / bylaws / fuel cost didn’t come into play would you glaze fire gas reduction or electric?

I was trimming pots today so I took a couple pics of the neoprene disc I trim on. Damp sponge on the wheelhead then plunk the neoprene on and another swipe to dampen the top.  I make a couple guide circles with my finger on the neoprene to help center the pot. I've been using the same disc for about 30 years. Sometimes the pot sticks so well I have to burp the edge of the disc to release the pot. I think the current cost is about $8 for one of these from Seattle Pottery Supply. (they come with an adhesive back now to put on a batt)
 

Clay wads not needed with neoprene to hold pots down, I don't know why more people don't use it.

I rest fingertips from my left hand on the pot and trim tool with my right. I use a neoprene pad to trim 99% of my pots on, no Giffin Grip.

I don’t know Rae, think your bad experience isn’t something you messed up on. You are too nice a person to anticipate someone being so nasty.  The rest of us, yeah, we messed up! 

This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt.  While throwing the donut press down firmly on the clay as you are pulling it outwards from center. 
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use  rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the  cut edge or let the sections dry a little then lay them facedown and smooth the cut edge. 
For mug handles pull them straight and let them hang until they are dry enough to attach. 
   
   

@Morgan, have you tried slaking some of your dry scrap and seeing if it actually needs additional plasticizer? If you have been diligent in saving your slops you might not need anything. Re which one to use if you do need one, Bentone MA is what used to be called Macaloid. I have used that and also  Veegum (it's not a gum either, it is a water washed white smectite clay, extremely fine particle size also).
If you do need to add some plasticizer I would weigh out a KG of dry scrap and then try just 0.50 - 0.75% of either Bentone MA (Macaloid) or Veegum. If you try the Veegum be careful which Veegum you get as there other forms of Veegum available, you want either Veegum or Veegum T. Whichever you use it has to be thoroughly mixed with hot water before adding to your slaked clay. I add the Bentone MA (or Veegum) to the water then whiz it with a handheld stick blender for about 20 minutes. It will go thick and very smooth, might need to add more water if it gels up too much. Once you have the dry clay slaked down add the Bentone MA or Veegum mixture to the clay slurry and continue mixing it until it's all blended. When trying out grolleg bodies I used 3% Veegum, it made a very plastic claybody that was quite sticky, I probably could have cut that amount back.
Hansen has the analysis for Bentone MA (aka Macaloid) containing MgO (approx 23%). Article on it here and on Veegum from Vanderbuilt minerals here. Either one will get the job done.

Rutile is one of those materials that can make or break a glaze, it can vary a lot from batch to batch. I would try it out with a small test batch before using it in a large bucket of glaze. Colour difference might just be your new batch hasn't been calcined. 

Rutile is one of those materials that can make or break a glaze, it can vary a lot from batch to batch. I would try it out with a small test batch before using it in a large bucket of glaze. Colour difference might just be your new batch hasn't been calcined. 

I shape simple extruded handles by  putting them inside oval cookie cutters. Extrude the strap, let it set up slightly so you can handle it without messing it up, then push it against the inside of the cookie cutter to get the shape. Leave it in there until it's set up enough that it will hold shape when you take it out. Makes a nice curve that's comfortable to hold. You can buy multiples of the same size cutter from folks on Etsy who 3D print them.

This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt.  While throwing the donut press down firmly on the clay as you are pulling it outwards from center. 
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use  rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the  cut edge or let the sections dry a little then lay them facedown and smooth the cut edge. 
For mug handles pull them straight and let them hang until they are dry enough to attach. 
   
   

This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt.  While throwing the donut press down firmly on the clay as you are pulling it outwards from center. 
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use  rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the  cut edge or let the sections dry a little then lay them facedown and smooth the cut edge. 
For mug handles pull them straight and let them hang until they are dry enough to attach. 
   
   

This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt.  While throwing the donut press down firmly on the clay as you are pulling it outwards from center. 
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use  rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the  cut edge or let the sections dry a little then lay them facedown and smooth the cut edge. 
For mug handles pull them straight and let them hang until they are dry enough to attach. 
   
   

This thread is bounced off this one that was discussing extruders then went off on a bit of a tangent. I brought up the subject of thrown handles as another alternative for @Pyewackette . (other options such as cast, press molded etc in the linked thread also)
Super quick demo photos below, hope this helps Pye.
Throw a donut on a batt, for mug handles that need to be straight use as big a batt as you have or throw on the wheelhead if it's wider than your batts. Center the clay then open it up right down to the batt.  While throwing the donut press down firmly on the clay as you are pulling it outwards from center. 
Clean up the edges of the donut and shape into a dome top, flat, ridged, whatever profile you need. Can use  rib made from an old credit/gift card to make identical profiles for the donuts if making a lot of one style that need to be the same.
Cut into the donut with a pintool then slowly rotate the wheel to cut the donut off.
At this point you can either let the donut set up a bit or work it now. Cut off a section and either hold it up and smooth the  cut edge or let the sections dry a little then lay them facedown and smooth the cut edge. 
For mug handles pull them straight and let them hang until they are dry enough to attach.