Slip trailing on top of ^ 6 glaze

[docweathers]

I know that slip trailing is usually done on green ware but like everything else, I'm gotta mess with a different approach.

I need a slip trailing formula that I can put over ^ 6 glaze which is over ^6 bisqueware.  I'm using Georgie's G mix 6/ grog. I've tried fiddling with some traditional slip trailing formulas but the shrinkage rate is so much different that my nice smooth lines turn into dashed lines as the trailing shrinks.

 

 

[neilestrick]

Slip is clay, so it follows the rules of attachment- no dryer than leather hard. Are you trying to trail on top of C6 glaze that has already been fired, or just after applying the glaze? What effect are you going for- just lines, or a raised surface?

[preeta]

Does it have to be slip? Are you willing to try underglaze?

it works both on ^6 raw glaze or fired glaze. On fired glaze underglaze does leave a slightly rough texture.  

Esp since you had a ^6 bisque. 

[Magnolia Mud Research]

To counter the shrinkage, I suggest that you calcine most of the clay used in your current recipe.    From something posted in the engobe chit-chats, my guess is about 75% of the clay should make it work.    Best approach is to do a line blend varying from all calcined to no calcined clay.  (you already have one point done).   See what happens.  

LT

[glazenerd]

Doc:

Have you tried the custom glaze suspender/brushing medium I sent you last year? It is all natural clay(s). Should work better in this case; but then again this is an oddity.

T

[docweathers]

Quote

 

Neil

I'm trying to draw raised white lines on top of raw glaze on top of bisqued clay

Preeta

No it does not have to be slip. Under glaze would be fine as long as I can apply it over a raw glaze on a bisque pot and it will give me a smooth raised line. Do you have a favorite under glaze formula that would do this?

Magnolia mud

I do have some calcinated  clay I could try.

Glaze nerd

I found your suspender very useful for a lot of things but I haven't given it a try for this. Maybe now is the time.

Thanks all for your suggestions

[preeta]

Aah doc! Raised lines! Nope not with underglaze that I know of.  I use Velvet U. Texturally they do stand out a bit on fired glaze  but not too much   

The only way I get raised lines is by using porcelain slip on wet clay.  No help to you unfortunately.  

Definitely LTs calcined clay should work. That’s the difference in schools slog for greenware and bisqueware. I would imagine testing is necessary.  

Do you have time for that?

[docweathers]

I'm just a beginner hobbyist so I have all the time in the world to test stuff.  So, it looks like calcination and glazed nerds brushing media are the answers.

[Magnolia Mud Research]

Take your base glaze and add 25% zircopax to the glaze.  Use this mixture to draw the lines.   

The zircopax acts as a  white colorant and at the high loading will stiffen the glaze.  An alternate scheme is to use a high level of titanium dioxide to do the same thing, i.e., whiten and stiffen the glaze.  Test test test.

 

[preeta]

Oooh brilliant thinking LT.  now I am going to try me some in a months time.  

Doc did you really mean you bisquesd to ^6 or was that a typo?

i thought you made a mistake of ^6 bisque and were trying to fix it.  

[docweathers]

Yes, I screwed up. I meant that it was ^6 clay that had been bisqued. I should have gone on to say that  I bisque  as ^04. 

 

If it continues to get any hotter,  I will just set my stuff out in the sun to bisque.

[preeta]

Ooh doc. But it’s a great opportunity to try out different things.  Been there done that. Hope no blowups!

Guess what though.  You just have to set your bisqueware outside to thoroughly heat up instead of using the oven or kiln before glazing. Yeah! We are going above a 100 today too. 105 exactly. Planning some cooking experiments using iron skillet and copper bottom pans. 

[docweathers]

I think I found the answer. It is a two-part solution. 

First, I tried putting a little, cellulose, as in paper Clay,  with quite a bit of CMC. This stopped the line from cracking into sections.. However, the whole line would peel up , sometimes actually pulling up most of the base glaze stuck to the bottom of my little white line. 

 

Second, To solve this, I'm now spraying the raw underlying glaze with a solution of CMC and letting it dry before applying the slip trailing.  This works wonderfully. My little white line does not break into sections and it stays down amazingly well.  In fact, it sticks down so well that it's really quite hard to scrape off, even when this procedure is applied to a very soft fluffy raw based glaze.