Lili Krakowski on fri 3 oct 08
I remain confused about this...both the slip recipes--Elise's and
Steve's--are pretty nonplastic. This suggests to me that if
Elise has a problem, and Steve does not, it is from something
beyond the slip recipe.
Application? If Elise puts on thin slip--and then adds two
coats of glaze--I wonder where all the water goes? We have been
told nothing about drying periods between applications and so on.
Nor how the ware is dried, how long, before firing.
Now if I were to test this all I would:
Make test tiles or pots:
1. Apply slip and glaze as now.
2. Apply slip only
3. Apply slip and one coat of glaze in the manner and time span
of today's applications.
4. Apply slip. Let dry for an hour or so. Apply one coat of glaze
5.Apply slip. Let dry an hour or so. Apply two coats of glaze in
manner and time span of today's application.
6. Apply slip. Let dry an hour or so. Apply glaze. Let dry 15
minutes or so, apply 2nd coat.
And now a stupid question. WHY is slip being applied to the
bisque if it is to be covered with two layers of glaze? Why not
apply the slip to greenware?
Lili Krakowski
Be of good courage
Steve Mills on fri 3 oct 08
Dear Lili,
In my case the slip was developed for applying to commercial biscuit fired tiles being used in workshops and classes for children. By adding colours to the slip this allowed them to explore slip trailing etc. without the teacher having to make lots of greenware tiles and keep them leather hard.
For myself I have found that when I have forgotten to apply white slip to a piece, a thin coat of white emulsion paint is a very good emergency "slip". After all, white emulsion is basically Titanium Dioxide and PVA glue with the odd anti-fungicide and matting agent thrown in!!
:-)
Steve
Bath
UK
--- On Fri, 10/3/08, Lili Krakowski wrote:
From: Lili Krakowski
Subject: peeling slip
To: CLAYART@LSV.CERAMICS.ORG
Date: Friday, October 3, 2008, 4:46 PM
I remain confused about this...both the slip recipes--Elise's and
Steve's--are pretty nonplastic. This suggests to me that if
Elise has a problem, and Steve does not, it is from something
beyond the slip recipe.
Application? If Elise puts on thin slip--and then adds two
coats of glaze--I wonder where all the water goes? We have been
told nothing about drying periods between applications and so on.
Nor how the ware is dried, how long, before firing.
Now if I were to test this all I would:
Make test tiles or pots:
1. Apply slip and glaze as now.
2. Apply slip only
3. Apply slip and one coat of glaze in the manner and time span
of today's applications.
4. Apply slip. Let dry for an hour or so. Apply one coat of glaze
5.Apply slip. Let dry an hour or so. Apply two coats of glaze in
manner and time span of today's application.
6. Apply slip. Let dry an hour or so. Apply glaze. Let dry 15
minutes or so, apply 2nd coat.
And now a stupid question. WHY is slip being applied to the
bisque if it is to be covered with two layers of glaze? Why not
apply the slip to greenware?
Lili Krakowski
Be of good courage
elise pincu on fri 3 oct 08
Hello all,
Thanks, Lili for your inquiries to get to the bottom of this. (And thanks to all those who have posted and tried to help)
I fire to cone 4 to get a nice, tight-as-can-be earthenware. I do dip leatherhard for small items. Larger items, I had a hard time - either dipping a large item or the worst - large, altered bowls ripping at the altered areas from the stress of re-wetting the leatherhard clay. So - I made up a bisque slip that seemed to work.
Good question about the applications. I usually dip the bisque, wait maybe 10 minutes, maybe less, before dipping in the glazes. I recently dipped a test tile in the bisque slip and left it, un-glazed. After hours, it was chalky. Maybe that is the culprit?
That excessive peeling didn't occur on the mug that I photoed, and I cannot remember if I maybe waited too long before coats on the casserole. I will dip the tile tomorrow and see what happens....
I have also thought of doing tests on adding more flux to the slip, though I am afraid the more glaze-like the slip, the more it may combine somehow with the glaze and no longer be a layer underneath the glaze.
By the way, I also attemped brushing slip on the larger wares instead of dipping (at leatherhard stage) and found that I didn't care for the brush strokes showing through and was unable to avoid them.
THanks again!
Elise
--- On Fri, 10/3/08, Lili Krakowski wrote:
> I remain confused about this...both the slip
> recipes--Elise's and
> Steve's--are pretty nonplastic. This suggests to me
> that if
> Elise has a problem, and Steve does not, it is from
> something
> beyond the slip recipe.
.....
John Rodgers on sat 4 oct 08
Elise,
For the purpose of applying a texture over DRY greenware, I have used a
sheet rock-mud texturing gun to spray the surface of the greenware with
slip to arrive at that texture. The process works great, no peeling when
drying, no peeling at bisque firing, nor any peeling when glaze firing.
Might it be possible that you could allow the work to dry, then spray an
overcoat of slip - made from the same clay - onto your work, using a
spray gun that does not texturize? It might be something worth trying.
If you use the same clay for your slip as for you pieces, you should not
have any problems, and, you could even add colorants to the clay -
metallic oxides and stains. Keep in mind however, that to stain clays
sufficiently for good colors it takes about 10% stain by dry weight.
Regards,
John Rodgers
Chelsea, AL
elise pincu wrote:
> Hello all,
>
> Thanks, Lili for your inquiries to get to the bottom of this. (And thanks to all those who have posted and tried to help)
>
> I fire to cone 4 to get a nice, tight-as-can-be earthenware. I do dip leatherhard for small items. Larger items, I had a hard time - either dipping a large item or the worst - large, altered bowls ripping at the altered areas from the stress of re-wetting the leatherhard clay. So - I made up a bisque slip that seemed to work.
>
> Good question about the applications. I usually dip the bisque, wait maybe 10 minutes, maybe less, before dipping in the glazes. I recently dipped a test tile in the bisque slip and left it, un-glazed. After hours, it was chalky. Maybe that is the culprit?
>
> That excessive peeling didn't occur on the mug that I photoed, and I cannot remember if I maybe waited too long before coats on the casserole. I will dip the tile tomorrow and see what happens....
>
> I have also thought of doing tests on adding more flux to the slip, though I am afraid the more glaze-like the slip, the more it may combine somehow with the glaze and no longer be a layer underneath the glaze.
>
> By the way, I also attemped brushing slip on the larger wares instead of dipping (at leatherhard stage) and found that I didn't care for the brush strokes showing through and was unable to avoid them.
>
> THanks again!
> Elise
>
> --- On Fri, 10/3/08, Lili Krakowski wrote:
>
>
>> I remain confused about this...both the slip
>> recipes--Elise's and
>> Steve's--are pretty nonplastic. This suggests to me
>> that if
>> Elise has a problem, and Steve does not, it is from
>> something
>> beyond the slip recipe.
>>
> .....
>
>
>
Lmiller on sat 4 oct 08
=20
BODY { font-family:Arial, Helvetica, sans-serif;font-size:12px; }=20
I have been trying to cover red/brown c6 stoneware with white
(&blue) slip for a while. I am looking for a smooth white surface
for color decoration and clear overglaze. I am keen on the way
Stangle pottery looks, nice crisp line carving thru the white slip.=20
Once I started trying to do this, I found all the problems recently
posted by Elise. Brushing the slip on seems to help reduce peeling
probably because of mechanical blending of the interface between body
& slip. When I used a slip on bisque, It gets a rougher texture than
I want. I adjusted my bisque slip to make it more of a glaze but it
isn"t really what I'm looking for. To keep this short ( I've wasted
a lot of time on this slip).=20
a. how green is green? black hard? can you dunk it? Stangle went
to spraying for a smooth slip=20
b. to defloc or not to defloc or to floc (my tests seem to indicate
defloc on black hard but not too thick.=20
c. how much plastic clay is in the greenslip version? I'm currently
testing 40, 50, 60 %.=20
Really like this discussion.=20
Larry Miller in N. MIch
Jeanie Silver on sun 5 oct 08
I haven't followed this thread in detail-but your last post made a few
things apparent...I believe your biggest problem is putting on the slip on
bisque and then putting glaze on the raw slip over the bisque surface...at
earthen ware temperatures, this is a recipe for disaster, causing the glaze
to crawl-sometimes disastrously. Outgassing, which is still going on at
earthenware temperatures as the glaze melts,causes crawling...
Itook a look at you photo, and I think that your problem is actually caused
by something else in addition. I have gotten that result when I used a slip
on bisque that did not have enough clay content to physically adhere to the
bisque. Then putting a glaze over the raw slip on top of a (probebly dry
bisque just exacerbates the problem. Its not a difference in shrinkage
rates so much as it is a lack of ability to adhere to the bisque.
for many years I have pursued earthenware with slip imagery and transparent
glazes...
this is what works for me:
!-make sure your slip is suited to your application...in many ways slip on
bisqueware is the least satisfactory application because it is hard to
modify and a bit tricky to get the thickness right...
I slip most things in a totally dry greenware state by dipping and pouring..
Not every claybody can handle this! Testing is very important! But many
eathenware terracotta bodies can handle this, if done correctly....I pour
the insides first and then wait-several hours or overnight...then pour the
outsides....I never never dip for this reason...the slip will seal moisture
in the claybody, causing bubbles beneath the slip and weakness in the
claybody. I then bisque the piece and proceed to glazing.
I never apply glaze to raw slip over bisque at earthenware temperatures,
and never if I can help it.
If you are having trouble with seams seperating when slip is poured, try
doing it on greenware instead of leatherhard. It sounds counterintuitive.
but may work for you. It does for me....
It also may mean that you need to work on the nstrength of your seams-you're
the best judge of that...
If I do use slip on bisque, I wet the bisque thourghly and thin the slip
somewhat.....
I hope this helps you..
Jeanie in Pa.
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