Slip Casting the Tumbler

Yesterday, alongside the goblet I also managed to slip cast my first tumbler using the three part mold I made last week.  This mold worked perfectly and the final piece was much easier to release from the mold and clean up than the goblet.  It was all over more structurally sound and I was very happy with the finished product.  I have now left it to dry before bisque firing.

  The two molds cast and waiting to dry for 15 minutes.
Cutting off the top edge with a potters knife.

With this piece I smoothed down all the inner and top edges with a sponge before taking it out of the mold.  This kept the all over strength of the piece.  I will be taking this approach with the run of all my final pieces.
 This is the piece straight out of the mold with the messy seams.

  This is the final result after cleaning with a sponge.
  There was some discussion about how thin the tumbler is.  I will be able to review this after firing.

First Goblet Sample

Today I was able to take my first goblet finished sample finished with a tin glaze Out the kiln.  I was very happy to see it standing, despite cracking at the base of the stem several times.  I was fairly happy with the finish however parts of the glaze hadn’t stuck because I should have stirred it a little longer.  I will sample more before choosing my final finish.

 I also managed to get my 3rd goblet out of the mold today.  I cut this to the edges at the top  to the edge of the glass as apposed to round in my first sample.

 So that the stem didn’t break I cleaned up most of the vessel whilst it was in partial parts of the mold to support it.  This approach worked very effectively.  The stem only wobbled slightly when I was putting the finishing touches to the piece.

 I finished of cleaning up this piece with a wet sponge which made this piece far neater than my previous two samples.  I feel that I am now heading towards the quality I am aiming for in my final pieces.

Tumbler Slip Cast Mold

Today I finished off making my tumbler slip cast mold.  I started my filing down the two parts I had made last week.  I keyed in 3 lock holes  and the cleaned and soft soaped the top surface.  Instead of drilling into the top section after casting as I had done with the previous mold, I built a clay cone on top.

 I then clamped around the wooden walls and sealed the edges with clay.

 After drying, I took off the wooden walls and then filed the sides down and scraped with a kidney.

 I am very pleased with the accuracy of this mold.  It has worked much better than the goblet mold as it was far less complicated to make.  I have left the mold to dry for three days before I will try using it for slip casting.

  

Goblet

I slipcast another Goblet last Friday.  As I had problems with the last one breaking I decided to cut the top section whilst it was still in the mold.  I had less problems with this one because the stem was stronger being cut in the mold.


This time instead of cutting the top round I cut the top in line with the walls which I think looks much better and will be more prcticasl cleaning.

Slip Casting the Tumbler

I have started to make the mold for the tumbler.  This was much simpler than the goblet design as it had much less undercuts within it.  The tumbler mold will only have to be in three parts as apposed to the five parts needed for the goblet.

Building the first side wall

 Building and clamping the wood walls and sealing sides with clay

  The first pour.
  The first mold taken apart.

  Cleaning up the first mold and adding the key holes.

 
 Building the wood walls and sealing for the second pour.

Clay Extrusion Machine

Yesterday I decided to 3D print myself a clay extruder from my home printer.  The first one I printed had a large internal area to hold the clay.  This would have taken 24 hours to print.  I re-designed it to take 12 hours and left this to run.  The print failed in the middle of the night when it had almost completed.  This was due to the plastic reel getting stuck.


I went back to the drawing board and reprinted another which was again a little smaller.  This took about 3 hours to print at the lowest quality.


The extrusion nozzle didn’t stick too well when printing, so I repaired this with my 3D printing pen.

I also realised that the pusher wasn’t strong enough with the flimsy stick I had added.  I eventually managed to extrude the clay with my thumb but this was quite difficult and so I will be making a much stronger pusher.


 I put together a few shapes with the clay I had extruded using some slip I made up.  This is just a sample, however it could be used as a tea-spoon rest.  I will fire and glaze this sample over the next few weeks.

I left this to dry a little and carved into it to smooth of the areas of leftover slip and lines from the printer.  A small section broke off where I didn’t join the pieces too well with slip.

Shot glass samples

I got back my shot glass samples from the second firing and glazing.  The red glaze was fired slightly too high and the colour burnt out.      I was however very pleased with the green.  It has a nice turquoise sheen to the surface.

    

Within the samples I experimented with different ways of glazing them.  Some of the samples had two coats anfd others had three.  I found that the ones that had three coats was too much and the glaze ran onto the kiln shelf.  Some of these broke when removing from the kiln and looked unsightly.  I shall therefore be glazing my final glasses with two coats.

  
This is my favourite design that I feel I will be using for the final run I will be making.  I have glazed the inside with white as it is non-toxic.

 Over the last few weeks I have also been re-printing the press molds at a greater size to take into account shrinkage.  I sampled this the other night.  I tried to make the walls a little thinner than in the samples so they will feel a little more delicate.  I had problems with one part of the top of the mold which has a deep overhang.  I cant remove the clay without this part ripping.  I have decided I will redesign this half of the mold and re-print it before making the full set.

Slip casting wine goblet

After leaving the mold to dry for several days I was able to use my slip cast mood today.  First of all I cleaned up the plaster with a wet sponge in order to get rid of any clay left from the mold making process.


I then drilled a hole in the top section of the mold in order to pour the slip in.  This was filed down and then smoothed out with a knife.


I mixed up the slip so that there was no lumps in.  This was then sieved into a clean bucket.



The mold was secured with rubber from a bike inner tube so it would stay together when casting.


The slip was then poured into the mold and left for 14 mins before poring back out.


 I filled the bottom of the goblet with more slip so that it would be easy to clean out after drinking from it. After leaving this for a while the slip level dropped so in the end I filled this other a ball of clay and some more slip.  This compromise now means that the stem is hollow however had I not done it this way I think the stem may have became too weak and may have collapsed whilst the clay was drying.



The slip was then left for two hours to harden a little before taking apart the mold.  I first scraped the clay from the pour hole in the top section.  I then carefully removed each part of the mold so as not to damage either the mold or the goblet.

  
I spent a few hours cleaning up the seams with a knife.  I had some trouble with the stem cracking under the weight of the top.  I am hoping I have filled this in and repaired it enough for it to survive the firing process.
I cut the top in a circular shape for this piece however I may change this to follow the lines of the outside on later models.



There was some splatter marks on the inside of the cup. This happened when trying to fill the base with slip.  I am hoping to get much neater as I make more.

 I think if there is one thing I had forgotten about the slip casting process it is that it takes a lot of time and patience.  I am hoping the final results will be worth all the time.