njabeid

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Well done!

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

Oh well, here's another try.
Dear Wise potters, thanks! You were right: after tweaking the engobe recipe, using local whitish clay as slip, slowing the bisque firing and also slowing the glaze firing now my pots have only some very small pinholes.
That involved some protracted procrastination, while I indulged in other techniques, and then 'forgot' to add cobalt to the glaze. That's now done. 
Three cheers! and thanks again.

 
 

OK, so the firing is done, and results and feelings are mixed. Somehow I feel lost and have forgotten where I was going.
Anyway, the cups and mugs were fired with Min's schedule, i.e. 110C to 700C no soak. 2) 50C to 900C no soak.  3) 42C to 1000C no soak. They all have the homemade slip ("K-slip).
1) K-slip brushed on while still damp, dipped in GT1 (my glossy transparent). No pinholes but cracks at the bottom, and a piece of slip missing. 

 
2) K-Slip sprayed while damp, sprayed GTI  + 0.3% CoCO3 . Kinda OK

3) K-slip + 10% WrSiO2 sprayed damp, and sprayed with GT1 + 3% CoCO3. (Inside is a poured commercial clear with added opacifiers. I was using it up. Lots of pinholes inside in nearly all. Something went very wrong with the pouring in this one.) There's a big kind of burst bubble and one pinhole.

4) K-slip + zirconium sprayed dry, and sprayed GT1. Definitely the best, albeit not any whiter, but very pinhole inside.

5) K-slip with 0.5% CoCO3 sprayed dry, and dipped GT1. 

6) I'm afraid I missed writing down the slip part, but it was applied dry and  sprayed with GT1 + 0.3 CoCO3. Clearly visible two little blow-outs; a few pinholes.
Coffee cups: 
One was dipped in K-slip while leather hard ... big mistake. It almost melted pathetically  to a puddle, handle cracked, but the result the front cup in the picture  is better than all the others, which were brushed with a hake brush; big mistake: I touched up the edges with the wrong glaze. All sprayed GT1 on the outside and poured opaque stuff inside. Better just have the same inside and out. Even waxed, edges are tricky with two glazes.

So -  conclusions:
1) The slower firing is good, I'll stick to it. But we changed two variables.
2) There is still a small issue with cobalt. My spray gun is a cheap thing, and makes the slip blotchy.
3) Slip works, but is far from white . Do I like the buff colour? It is too  coloured to take colour kindly, but I'm going to try adding some yellow iron oxide to push it a bit further into a more interesting look.  Maybe try something besides cobalt.
4) I didn't dip any dry pots - must check whether the stencil will stay on.
5) I wonder why the interiors pinholes so badly. Need to make the surface smoother.
There's more to work on, but thanks to you all I have learnt a lot and am on a track to improvement.
These cheered me up a bit though:

Thanks!!
 
 

@Bill Kielb sorry, I’m afraid I don’t use cones here, The discussion has been more about pushing the firing time to get rid of the carbon etc. It looks positive, combined with a change in the white coating.

OK, so the firing is done, and results and feelings are mixed. Somehow I feel lost and have forgotten where I was going.
Anyway, the cups and mugs were fired with Min's schedule, i.e. 110C to 700C no soak. 2) 50C to 900C no soak.  3) 42C to 1000C no soak. They all have the homemade slip ("K-slip).
1) K-slip brushed on while still damp, dipped in GT1 (my glossy transparent). No pinholes but cracks at the bottom, and a piece of slip missing. 

 
2) K-Slip sprayed while damp, sprayed GTI  + 0.3% CoCO3 . Kinda OK

3) K-slip + 10% WrSiO2 sprayed damp, and sprayed with GT1 + 3% CoCO3. (Inside is a poured commercial clear with added opacifiers. I was using it up. Lots of pinholes inside in nearly all. Something went very wrong with the pouring in this one.) There's a big kind of burst bubble and one pinhole.

4) K-slip + zirconium sprayed dry, and sprayed GT1. Definitely the best, albeit not any whiter, but very pinhole inside.

5) K-slip with 0.5% CoCO3 sprayed dry, and dipped GT1. 

6) I'm afraid I missed writing down the slip part, but it was applied dry and  sprayed with GT1 + 0.3 CoCO3. Clearly visible two little blow-outs; a few pinholes.
Coffee cups: 
One was dipped in K-slip while leather hard ... big mistake. It almost melted pathetically  to a puddle, handle cracked, but the result the front cup in the picture  is better than all the others, which were brushed with a hake brush; big mistake: I touched up the edges with the wrong glaze. All sprayed GT1 on the outside and poured opaque stuff inside. Better just have the same inside and out. Even waxed, edges are tricky with two glazes.

So -  conclusions:
1) The slower firing is good, I'll stick to it. But we changed two variables.
2) There is still a small issue with cobalt. My spray gun is a cheap thing, and makes the slip blotchy.
3) Slip works, but is far from white . Do I like the buff colour? It is too  coloured to take colour kindly, but I'm going to try adding some yellow iron oxide to push it a bit further into a more interesting look.  Maybe try something besides cobalt.
4) I didn't dip any dry pots - must check whether the stencil will stay on.
5) I wonder why the interiors pinholes so badly. Need to make the surface smoother.
There's more to work on, but thanks to you all I have learnt a lot and am on a track to improvement.
These cheered me up a bit though:

Thanks!!
 
 

@Babs I have one, it’s super useful, but the rate of drying is mind-bending, Including one’s skin!

It's the Sahara. Look up Nouakchott.
Yesterday I wrote a post that doesn't seem to have been uploaded. It was about the ongoing tests. Various methods of applying the home-made slip, and various glazing methods and additions are all now cooling in the kiln. I'm very excited and hope it will not be too disappointing. True, several variables are changed at the same time (firing schedule, slip, additions, application methods, but it will be interesting and open up new avenues of research.
This was the bisque fired pots, looking good.

OK, so the firing is done, and results and feelings are mixed. Somehow I feel lost and have forgotten where I was going.
Anyway, the cups and mugs were fired with Min's schedule, i.e. 110C to 700C no soak. 2) 50C to 900C no soak.  3) 42C to 1000C no soak. They all have the homemade slip ("K-slip).
1) K-slip brushed on while still damp, dipped in GT1 (my glossy transparent). No pinholes but cracks at the bottom, and a piece of slip missing. 

 
2) K-Slip sprayed while damp, sprayed GTI  + 0.3% CoCO3 . Kinda OK

3) K-slip + 10% WrSiO2 sprayed damp, and sprayed with GT1 + 3% CoCO3. (Inside is a poured commercial clear with added opacifiers. I was using it up. Lots of pinholes inside in nearly all. Something went very wrong with the pouring in this one.) There's a big kind of burst bubble and one pinhole.

4) K-slip + zirconium sprayed dry, and sprayed GT1. Definitely the best, albeit not any whiter, but very pinhole inside.

5) K-slip with 0.5% CoCO3 sprayed dry, and dipped GT1. 

6) I'm afraid I missed writing down the slip part, but it was applied dry and  sprayed with GT1 + 0.3 CoCO3. Clearly visible two little blow-outs; a few pinholes.
Coffee cups: 
One was dipped in K-slip while leather hard ... big mistake. It almost melted pathetically  to a puddle, handle cracked, but the result the front cup in the picture  is better than all the others, which were brushed with a hake brush; big mistake: I touched up the edges with the wrong glaze. All sprayed GT1 on the outside and poured opaque stuff inside. Better just have the same inside and out. Even waxed, edges are tricky with two glazes.

So -  conclusions:
1) The slower firing is good, I'll stick to it. But we changed two variables.
2) There is still a small issue with cobalt. My spray gun is a cheap thing, and makes the slip blotchy.
3) Slip works, but is far from white . Do I like the buff colour? It is too  coloured to take colour kindly, but I'm going to try adding some yellow iron oxide to push it a bit further into a more interesting look.  Maybe try something besides cobalt.
4) I didn't dip any dry pots - must check whether the stencil will stay on.
5) I wonder why the interiors pinholes so badly. Need to make the surface smoother.
There's more to work on, but thanks to you all I have learnt a lot and am on a track to improvement.
These cheered me up a bit though:

Thanks!!
 
 

You may have to become nocturnal.

For some reason my posts seem to be disappearing.
@BabsThanks, I have one - it's just a bit Mario Bros working with clay drying around the edges in minutes. And hands!
@Min I'm being optimistic. You never know, something could work out. Anyway, my pots never ever turn out the same as test tiles.

@Min Thanks! I’m being optimistic. Some might even turn out OK…

Seems a shame to use such nice pots for testing.

@Min Thanks! I’m being optimistic. Some might even turn out OK…

It's the Sahara. Look up Nouakchott.
Yesterday I wrote a post that doesn't seem to have been uploaded. It was about the ongoing tests. Various methods of applying the home-made slip, and various glazing methods and additions are all now cooling in the kiln. I'm very excited and hope it will not be too disappointing. True, several variables are changed at the same time (firing schedule, slip, additions, application methods, but it will be interesting and open up new avenues of research.
This was the bisque fired pots, looking good.

It's the Sahara. Look up Nouakchott.
Yesterday I wrote a post that doesn't seem to have been uploaded. It was about the ongoing tests. Various methods of applying the home-made slip, and various glazing methods and additions are all now cooling in the kiln. I'm very excited and hope it will not be too disappointing. True, several variables are changed at the same time (firing schedule, slip, additions, application methods, but it will be interesting and open up new avenues of research.
This was the bisque fired pots, looking good.

It's the Sahara. Look up Nouakchott.
Yesterday I wrote a post that doesn't seem to have been uploaded. It was about the ongoing tests. Various methods of applying the home-made slip, and various glazing methods and additions are all now cooling in the kiln. I'm very excited and hope it will not be too disappointing. True, several variables are changed at the same time (firing schedule, slip, additions, application methods, but it will be interesting and open up new avenues of research.
This was the bisque fired pots, looking good.

@Min
I always use Epsom salts, but so far have not felt the need to deflocculate anything. I'm sure I'll find something.

Products that are sold specifically as washing soda usually have other ingredients added to them that will really mess with your glaze bucket, so it might not be the end of the world.
Can you get your hands on some Dispex from any of the places you get materials from? Because that would be the ideal stuff for the job, and a little goes a long way. Even if someone has to bring a 1l bottle in their checked bag, it’ll last you a looooong time.