Jump to content

How to smooth the surface of detailed work at greenware stage?


Recommended Posts

I applied iron oxide at leather (very) hard stage, as I have not had good luck applying it on bisqueware under glazes. The iron oxide was sponged off (kitchen-type) so as to work with the pieces as little as possible, because the detailed coils were rather dry and prone to split.

The bowls feel chalky, grittier than I like. Using a scotch-brite scrubby works a little, but I suspect there is a better way. Should I wait until the pieces are bone dry?

I'd sure appreciate suggestions on smoothing the flat parts of the bowls, and the detailed parts too, although I'm concerned about touching them more than I have already.

IMG_5199.jpg

Link to comment
Share on other sites

2 hours ago, Bendan Blue said:

I applied iron oxide at leather (very) hard stage, as I have not had good luck applying it on bisqueware under glazes. The iron oxide was sponged off (kitchen-type) so as to work with the pieces as little as possible, because the detailed coils were rather dry and prone to split.

The bowls feel chalky, grittier than I like. Using a scotch-brite scrubby works a little, but I suspect there is a better way. Should I wait until the pieces are bone dry?

I'd sure appreciate suggestions on smoothing the flat parts of the bowls, and the detailed parts too, although I'm concerned about touching them more than I have already.

IMG_5199.jpg

I guess my suggestion would have been to smooth with a damp sponge first then iron oxide as you say at leather hard then bisque. If it’s still too rough after bisque, you can lightly sand smoother for any real rough spots being careful not to remove too much iron oxide. If this is clay with grog, smoothing with a damp sponge will often raise the grog and make it feel rough. So as much smoothing as practical while building, decorate then any minor touch up with a damp sponge at bone dry stage, then maybe select sanding after bisque seems about the best you could do. Any sanding definitely needs personal protection and an appropriate place to do it so it does not affect folks nearby.

The other possibility would be to burnish the flat areas with a metal or plastic  rib at the greenware stage and then move on to decorate. Probably needs to be put on a wheel though and carefully burnished.

You could also  wash accent similarly with many underglazes if the iron oxide is too messy.

Link to comment
Share on other sites

It is B-Mix (not the added grog version), and was pressed smoother before the application and sponge removal of FeO2, so curious as to why it's more chalky now.

I tried burnishing at his stage, but that was shifting  the FeO2 application and was hard to not mush some subtler design attributes on the flat areas. I'll go with a light sand after bisque fire, and hope glaze application helps a little. Thanks for the suggestions!

Link to comment
Share on other sites

What you are planning seems the best you can do to rescue this piece. If you make more, smooth the leather hard bowl surface with a flexible rib before adding the coils and then protect it with dry cleaner plastic (cut to fit) to protect the smooth surface from drips and prints while you apply the coils. Sanding and sponging unfired clay removes the finer particles, exposing the coarser ones. 

Put the oxide or thinned glaze wash on bisqued clay, then you can wash off the excess without changing the surface. Warning: the clay will seem less smooth after bisque, however, trying to make it even smoother by sanding at this point will be counterproductive, leaving dust to interfere with the glaze. Depend on your glaze to bring smoothness to the finish.

Link to comment
Share on other sites

Suggestion: Take some of your B-mix clay body and make some terra-sig from it.  mix a few lumps of clay body with some water until you get a thin white broth; add a pinch of soda ash as deflocculant and let the big heavy particles (mostly silica and feldspars) sink to the bottom.  (I just let it sit for a while and then skim the white liquid from the sludge in the bottom).  Use the skimmed liquid as your terra-sig. The idea here is to get a thin slip consisting primarily of clay particles rather the normal clay slips. If the slip is too 'thin' let it evaporate a while.    (If you need a cook-book check out the terra-sig method from Vince Pitelka http://www.vincepitelka.com/wp-content/uploads/2019/05/Super-Fine-Terra-Sigillata-Edited-2019.pdf or Marcia Selsor's method https://www.marciaselsorstudio.com/how-to-make-terra-sigillatta.html  ) 
Add some iron oxide to the B-mix terra-sig to meet you iron requirements and mix thoroughly. 

Make some test pieces to practice the application. 

Apply this well mixed clay and iron oxide to your ware items after the ware has reached stiff leather hard.  Apply thin layers of the iron-clay slip with a brush or sponge-brush.  When the shine disappears from the applied slip, compress and burnish the area with you fingers or with a plastic sheet such as a sandwich bag or piece of saran wrap; the idea is to compress the surface hard particles (iron oxide) into the thin soft clay layer;  repeat as needed to get the colorant level and texture to your satisfaction. 

I have used terra-sig on stoneware to produce smooth surfaces on the foot areas of sculpture ware and bowls.  

LT 

Edited by Magnolia Mud Research
Spelling
Link to comment
Share on other sites

 

3 minutes ago, Bendan Blue said:

Thank you! When applying oxide to bisqueware, is there a way to do so that it doesn’t blend up in the glaze?

If you are asking to keep the iron oxide from being "migrating" into the wet glaze as the glaze is being applied, the only way i know to prevent that is to bisque the ware again before glazing.  Some colleagues have had some success at preventing the stains from moving by spraying the glaze.  

LT  

Link to comment
Share on other sites

that is a very nice bowl, the decoration is just right but yes, you should have left  the flat surface alone,    every time you touch it, you make a mark.   follow rae's suggestion on the next one.  if you use a darker glaze on this one, it could be spectacular.  leave it alone at this point and just glaze it darker.   you have not indicated what kind of glaze  you plan to use.

Link to comment
Share on other sites

Re glaze, I was waiting to see how these bowls developed - awaiting inspiration, as it were. I use commercially prepared glazes. It's always a conundrum - how to get enough glaze on over most of the bowl without burying the finer detail coil work.  The bowl shown below had fatter coils, and no tiny details down the sides of the bowl. These new ones seems more challenging, was almost considering a clear. I'd love your glazing suggestions (color, brand) ,  have plenty of test tiles to try them out.

IMG_4251.jpg

Link to comment
Share on other sites

from your reply, i assume you use brushes.   if i were to glaze that big fruit bowl, i would brush a colored  glaze normally on the large,  flatter part.  then i would put some of the same glaze straight out of the bottle into a different container and thin it.   brush that on the details and fire.   then love the result.  if you ask ten people you will get eleven answers on doing it better.

the only commercial glaze i use is stroke & coat from mayco.   i use a very small amount to do the purple dragonflies on my work.   i also use them to detail empty bowls.   otherwise i make glaze from very good sources, Min on this forum for example.

Link to comment
Share on other sites

Couldn't find the Min you referred to? I'm interested in glaze making, might be the next fun thing to learn. Currently learning to operate a manual kiln, so could be a while.

Been using Coyote, Duncan, Amaco since I do work so little work.

Oldlady, could you post a picture of a piece where you did just what you suggested - full strength on the body, half strength on the detail work?

Link to comment
Share on other sites

Welcome to the forum Bendan.  If you wish to see examples of Oldlady's work, click on the image of her profile, then look for the file tabs in her profile and click on Albums. In there you will see how there are areas of texture with thinner glaze.  

 

I do several pieces there I have had a need to expose or highlight texture. Sometimes I will use a wash made up of a frit, and clay with some coloring oxide like Iron oxide, or cobalt carbonate, or copper carbonate.  After applying the wash I would then wash off the high areas, and use some form of transparent glaze overtop. Sometimes I do the same and use an light colored transparent glaze over top. It takes knowing your glazes, which takes lots of glaze testing, on test tiles and then on test pieces to see just what will work best.

Another technique to explore is spray glazing where you angle two different glazes on to an area so that one edge of a texture has one color and the opposite edge another. Works really well with glazes that have a tendency to break over texture.

 

 

 

best, 

Pres

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.