Assembling Clay Boxes

[Zuni]

I've been working in clay for a few years, but have just started making boxes. No matter what I do, when I put the sides together, and meld them together - using either my fingers or a tool, I get marks in the clay that I have trouble removing. Any ideas?

[Chris Campbell]

It's just a matter of practice and waiting till the slabs are just right. You might be working

a little too soon or using too much liquid in the joins. Use just a little vinegar in your water

and you will find you need less.

 

Try scoring, slipping putting them together then doing all the work on the inside surface

leaving the outside alone. Think about not touching it and work the inside. It will hold together

and you can come back later when it stiffens and fix any little blips.

[Zuni]

It's just a matter of practice and waiting till the slabs are just right. You might be working

a little too soon or using too much liquid in the joins. Use just a little vinegar in your water

and you will find you need less.

 

Try scoring, slipping putting them together then doing all the work on the inside surface

leaving the outside alone. Think about not touching it and work the inside. It will hold together

and you can come back later when it stiffens and fix any little blips.

 

 

Thank you! Can't wait to get home to try it...

[azjoe]

FWIW, my slab building results improved when I...

 

1. cut my fingernails really short... this stopped those little dents that seemed to appear everywhere.
2. paid more attention to how I handled the clay after rolling the slab... anything which deforms the flat slab to a shape other than you eventually desire has the potential to embed stresses which will potentially work against you later.
3. understood that better results are obtained when all the component pieces of clay used to construct a piece are at the same level of dryness... this dramatically reduces the chances of cracking, warping, etc. When it's impossible to do this it's prudent to spritz the partially assembled piece to prevent it from becoming much dryer than the parts you're still fabricating to add to the piece.
4. paid more attention to cutting slabs to the exact size and edges to the correct angles for assembly... this helped avoid gaps and uneven joints that needed to be repaired with additional bits of clay. Unevenness occurs when the clay is not uniformly dense when fired... compressing clay to remove a bump, pushing/stretching to fill a hollow, and filling dents and large cracks with slip all work against having the clay in the repaired area uniformly dense with the rest of the piece.
5. stopped using slip as a "gap filler"... this avoided those annoying "depressions" in the filled areas when the piece dries (due to the different water content of the slab and the slip... ie, the slip shrinks more than the slab and even if the greenware looks smooth, bisque and glaze firing will often cause depressions to appear since the extra moisture in the clay slip leaves less dense clay in that area which shrinks more during firing).
6. learned to let my slabs dry more before assembling the piece... this reduced unintentional dents, finger depressions, etc. which later had to be filled/fixed somehow.
7. learned to provide support if needed for assembled pieces until they dry enough to support themselves... this reduces the "fussing" you have to do to keep reworking the piece if it sags during assembly or drying which often introduces more dents, cracks, etc. which then have to be repaired. Crumpled newspaper, pieces of foam, lumps of clay, etc. all have usefulness to help support and maintain the shape of your piece until it dries enough to stand on its own.
8. learned that slow drying is well worth the time if you're not in a hurry. Some of my best pieces were left under loosely draped plastic until they were almost completely dry.

All that said, it's an imperfect world and we do what we have to do. On average, things seem to work best for me when I roll slab(s) and then lay newspaper and a board on top of each and flip it over to transport to the assembly table. When I have ALL the slabs I need at the table, I smooth/compress each slab with a rib (I actually use an old credit card instead of a rib... it has the right "flex" for me). I then lay newspaper and board(s) on top and flip each over to do the other side. I then let them sit to get appropriately dry for assembly... I like medium cheese hard for boxes, less dry if the slab must be curved to a small radius. About half way through this drying process I cut the slabs into the size pieces I need (allowing for shrinkage if exact dimensions in the finished piece are necessary), then bevel the edges to the angles needed for assembly (eg, 45-degrees, etc.), and lightly touch up the slab faces with the rib as needed. For assembly, I use magic water or Darvan 7 (instead of slip) most of the time. I mostly fill dents and other areas needing buildup with bits of excess clay from the slabs the pieces were cut from (using magic water as the "glue") and then cut/shape with various tools to match the surrounding contour. When I do use slip as a filler, it's usually thick... I mound it up a bit and let the moisture content in the slip and surrounding clay equalize, then use a tool or scraper to cut away the excess. YMMV

[JSWski]

I always like to add a coil on the inside seam to strengthen the seam, but that, too, can create more fuss & muss. Having a right angled support (if creating 4-sided boxes) can be a big help. I like the jig featured in one of the make-your-own tool articles: http://ceramicartsdaily.org/clay-tools/making-clay-tools/the-right-angle-for-approaching-geometric-ceramic-sculpture/

[Marcia Selsor]

Thanks. I wrote that article about the jig. I made my first right angle jig about 40 years ago. "Necessity is the mother of invention". I needed a way to support large pieces while they set up.

I use bevel cuts on corners, slip and then press together. I add the could on the inside seam after smushing the fingernail blend from one side then the other.

I use a rib to smooth out the seem.

 

On the outside I sometimes clean up imperfections with a piece of hacksaw blade by cross hatching and then smoothing.

 

Marcia Selsor

[Pres]

I've been working in clay for a few years, but have just started making boxes. No matter what I do, when I put the sides together, and meld them together - using either my fingers or a tool, I get marks in the clay that I have trouble removing. Any ideas?

 

 

For years I used standard slip to join seams with a reinforcing coil blended inside, then slip with a little vinegar. The improvement helped the kids with better joins. Then about 10 yrs ago I came across "magic water" Sodium Silicate and potash mixture. Better cleaner seams, and neater all the way around. I still had them blend in the reinforcing coil, but everything held together better with very few open seams. Survival was 99.5% before, but often there would be a weak join here or there. With the "magic water" that did not happen.

[Marcia Selsor]

I agree. I use magic water. I made a gallon of it years ago and still have some. I have never tried straight Darvon 7 as Azjoe mentions. Can't say abut that.

I use Lana Wilson's recipe sometimes I use a vinegar slip. Vinegar penetrates the plate particles of clay with less space than water...making for a tighter slip.

Magic Water from Lana Wilson

1 gallon water

9.5 grams sodium silicate

3 grams soda ash

Marcia

[Mossyrock]

I agree. I use magic water. I made a gallon of it years ago and still have some. I have never tried straight Darvon 7 as Azjoe mentions. Can't say abut that.

I use Lana Wilson's recipe sometimes I use a vinegar slip. Vinegar penetrates the plate particles of clay with less space than water...making for a tighter slip.

Magic Water from Lana Wilson

1 gallon water

9.5 grams sodium silicate

3 grams soda ash

 

Marcia

 

 

This is the recipe I use. Amazing stuff. I also use it instead of water when making a batch of slip and have seen a huge difference in the way handles adhere to mugs and seams join when handbuilding.