Min

I rarely need to level the base of a pot, if the pot has a foot ring (most om mine do) I don't try and level the entire base. I trim as usual then when I have the foot ring trimmed to width I trim a bevel into both the inside and outside of it then just use a loop tool to cut off the tip of it. Since it's just a very small amount of clay getting cut off it's easy to hold the tool level to do this.

 

IMHO that really does looks like a bloat/bleb from an air bubble in the clay wall. When the glaze melts it seals the clay over so the gas can't escape and you get those bloats/blebs. 
After wedging your usual way try slicing a few chunks of clay up into thin slices and look for air pockets. Keep doing this until you can wedge without getting them. Try cut and slam wedging also if you don't already do this.
I'ld also suggest doing some absorption tests on your claybody given it is being fired below it's maturity, how to that here if you need it, about 2/3 the way down.

The only thing that might make a difference is the slight increase in silica but my hunch is it won't be significant enough to make a difference, testing will tell.
Given there is no added standalone silica in the recipe to reduce it and get closer to an identical UMF you would need to reduce some of the silica while keeping the other oxides balanced. This is what the Target and Solve function did with it, reduced the silica by reducing the Nepheline Syenite then increased the Minspar (it has less silica than Nepheline Syenite) to rebalance the Sodium and Potassium then adjusted the Ball Clay to adjust the alumina and rebalance the silica. 
As well as how the glaze behaves in the bucket particle size and how well they melt comes into play also. 

This came up the other day, might help. https://community.ceramicartsdaily.org/topic/41668-midfire-clay-short-when-recycled/  Given your reclaim is already on plaster slabs if it is still fairly wet I'ld put it back into a bucket with some more water and add the blunged bentonite or ball clay/bentonite and slurry mix it again with the plasticizers. The smaller the clay particles the greater plasticity you will get from them, bentonite is much finer than ball clay which in turn is much finer than EPK. 

Yeah, I'm thinking in this case that might not work as well for the OP here as they are looking to speed up the drying time and defloc's slow it down.

The only thing that might make a difference is the slight increase in silica but my hunch is it won't be significant enough to make a difference, testing will tell.
Given there is no added standalone silica in the recipe to reduce it and get closer to an identical UMF you would need to reduce some of the silica while keeping the other oxides balanced. This is what the Target and Solve function did with it, reduced the silica by reducing the Nepheline Syenite then increased the Minspar (it has less silica than Nepheline Syenite) to rebalance the Sodium and Potassium then adjusted the Ball Clay to adjust the alumina and rebalance the silica. 
As well as how the glaze behaves in the bucket particle size and how well they melt comes into play also. 

The target and solve function is supposed to get you a chemically identical recipe, one that will *theoretically* look the same. And that’s what’s happened here: all the ratios except for the calculated expansion in the first example are identical, and even those are only off by the faintest amount. 
However, target and solve doesn’t address bucket behaviour, which affects how a glaze applies to the pot, which in turn can affect the final look. Bucket behaviour is affected by things like changes in the total amount of clay, or in the amount of soluble materials. The total amount of clay in the target and solve recipe is a few percent higher than the original, and there’s a bit more soda ash. Not a lot in either case, but it could make this version a bit more prone to crawling than it already is, if applied thickly. 
The straight substitution recipe only has marginally more silica, and a slightly different expansion rate. But again, those changes are small, and any differences in the look of the glaze might depend on the clay body (crazing from expansion rate) and the firing cycle (gloss level from additional silica).
 
Best advice from here is to try them both and see which one you like better. Glaze software eliminates some physical testing, but  not all. 
 

Given this is a smooth white claybody that fires up to 1280C it could very well be the reclaimed clay just wasn't wedged properly. With pyroplastic claybodies if you don't get all the air bubbles out the clay what can happen during glaze firings is the air pockets expand and cause a bloat (sometimes called a bleb). Are you getting the problem more often with the recycled clay? 

Hi and welcome to the forum.
What do you show just doing a one for one swap? This is what I get using Insight with their materials database.

Given this is a smooth white claybody that fires up to 1280C it could very well be the reclaimed clay just wasn't wedged properly. With pyroplastic claybodies if you don't get all the air bubbles out the clay what can happen during glaze firings is the air pockets expand and cause a bloat (sometimes called a bleb). Are you getting the problem more often with the recycled clay? 

Yeah, I'm thinking in this case that might not work as well for the OP here as they are looking to speed up the drying time and defloc's slow it down.

Agree with you that gum(s) are great for hardening powdery raw glazes and with some glazes that just don't want to layer up without lifting. I'ld hazard a guess there is much more gum in a commercial brushing glaze than what would be in a dipping glaze to prevent those issues though.

This came up the other day, might help. https://community.ceramicartsdaily.org/topic/41668-midfire-clay-short-when-recycled/  Given your reclaim is already on plaster slabs if it is still fairly wet I'ld put it back into a bucket with some more water and add the blunged bentonite or ball clay/bentonite and slurry mix it again with the plasticizers. The smaller the clay particles the greater plasticity you will get from them, bentonite is much finer than ball clay which in turn is much finer than EPK. 

I agree that stacks of test tiles can get fiddly and overwhelming but tests are so useful! I’ve made simple reference pots for my stain tests using bisque, straight-sided mugs, cups or bowls of the preferred clay, one for each base glaze, and as many small deli cups as you have stains to test.
Dip the pot almost halfway into the glaze and let dry.
Mix 1/8 tsp of stain into 1T of base glaze in each carefully marked deli cup and stir up, add a little water to make it brushable, if needed.
Paint 1/2” wide vertical stripes of each color from top to bottom, over the dipped glaze and over the bare clay.
Dip the bare end of the pot almost halfway into the base glaze, covering the stripes, and let dry. There will be a space between dips to show you what the stain in a bit of base looks like on bare clay - handy for white clays.
After the firing, use a sharpie to label the stain stripes with the stain numbers. Make notes if you want to try different proportions in a future test.
I use these little deli cups to decorate from, mixing more as needed (stains are expensive!) and letting them dry up between uses, adding water by drops to rehydrate.
NOTE: be sure you make note on the pot of which end is Glaze Over and which is Glaze Under. It won’t always be obvious  
 
 

I wouldn’t use either of those glazes if you are new to glaze chemistry as it would be necessary to remove some of the other fluxes in order to add zinc. If you just added zinc then the glaze would have more flux than needed to create a balanced glaze. Result would be an excessively fluid glaze.
Glazes high in magnesium tend to have a more muted response to colourants than those without high levels of it and blues  from cobalt lean more towards purple tones.
Yes, zircopax will give more of an opaque glaze, with or without stains. Starting at around 5% addition will show, 10% will be opaque on most bodies. 
A green stain that contains chrome when put in a glaze containing zinc will most often give an unpleasant brown.
Your second link didn’t work for me.
Welcome to the forum.

Pinched your fingers yet? (yup, I've done that a few times )

For future searching, please note this should read Giffin Grip.  No "r", "i" not "e".   

Pinched your fingers yet? (yup, I've done that a few times )

I question the testing using the same piece for each subsequent heat increment as each cycle will stress/shock the glaze. I know that's the point but I agree with Hansen's take on this. I sometimes go 300F/ice water, then 315F/ice water then 325F/ice water. If a glaze doesn't stress craze from this I don't think it will with everyday normal (sane) usage. 450F to ice water IMHO is far too extreme! We are after all making ceramics, not metal bakeware. It does seem logical to soak the test piece for 12 hours after a reasonable stress/shock testing though.
edit: In the past I did try the boiling water / ice water testing, had a glaze that passed it so went ahead and glazed a load of pots with it which later went on to craze. I'm sticking with the oven/ice water test, greater difference in temp therefore a harsher test, either the one above or just 3 sets of samples at 315F. 

Pinched your fingers yet? (yup, I've done that a few times )

I question the testing using the same piece for each subsequent heat increment as each cycle will stress/shock the glaze. I know that's the point but I agree with Hansen's take on this. I sometimes go 300F/ice water, then 315F/ice water then 325F/ice water. If a glaze doesn't stress craze from this I don't think it will with everyday normal (sane) usage. 450F to ice water IMHO is far too extreme! We are after all making ceramics, not metal bakeware. It does seem logical to soak the test piece for 12 hours after a reasonable stress/shock testing though.
edit: In the past I did try the boiling water / ice water testing, had a glaze that passed it so went ahead and glazed a load of pots with it which later went on to craze. I'm sticking with the oven/ice water test, greater difference in temp therefore a harsher test, either the one above or just 3 sets of samples at 315F. 

Pinched your fingers yet? (yup, I've done that a few times )

My guess would be it's because of different reflected indexes between the glazed and unglazed surfaces while in the microwave. 

Hi and welcome!
Stains are fun to work with, especially for us dark clay users. And the reference chart you’ve already found is a very good reference is this section of Digitalfire. Tony identifies the stain by number, which is a good practice as there are 3 different numbered stains with the name “dark red” and they all have slightly different chemistry.Tony’s got examples of the Canary Yellow and Turquoise in a magnesium matte glaze base, so you can see how those 2 respond, at least.
Speaking of recipes: the second  link you’ve shared comes back as a “does not exist” error. If this is a recipe on your own page, make sure it’s published so we can see it. 
Zircopax won’t make the colours pastel: glaze colour theory doesn’t work the same as paint. If anything, it’ll make it brighter and more saturated, because more of the colour is reflected back to your eyes. 
 

Maybe you mean ASTM 554? It calls for three passes of going from 250F to room temperature water without crazing. Repeat at +25F increments up to 450F. Crazing fails the test. Too much work for me!  I just rely on three passes of boiling water to ice water to determine whether it's going to craze or not. It is a little bit more of a cheat for me because boiling water at my altitude is only 199F. Although the microwave test calls for doing ASTM 554 first, to me, the two tests seem mostly independent.  If you are going to determine whether a piece is microwave safe, microwaving it and seeing if it gets too hot seems to be enough for me.