Jump to content


Member Since 08 Feb 2012
Offline Last Active Yesterday, 08:33 PM

#88012 Mold Making

Posted by perkolator on 29 June 2015 - 05:39 PM

DO NOT use grease, WD-40, vaseline or any other oil-based substance like suggested above, as your mold release.  The whole point of using plaster is to take advantage of the capillary/wicking action of the material, to pull water from the clay and set it up faster - if you go and use something oil-based as a mold release, you've now clogged the pores and severely diminished capillary action, if any at all.  


Use actual "mold soap" or purelube/greensoap, which are the products that should be available from any ceramics supply.  Alternative is diluted Murphy's Oil Soap.

  • Min likes this

#80294 The Dirtiest Job In Ceramics

Posted by perkolator on 28 April 2015 - 01:59 PM

Cleaning sink trap has got to be #1 only based on the smell.


A very close contender is making a batch of clay with a super-smelly reclaim barrel which smells as bad as a sink trap, because it's full of dead skin cells, newspaper bits, etc and has been sitting in the sun for a few weeks....and you're putting your bare hands in it...and your head goes into or very close to the trash can because you're reaching to the bottom...at least with the sink trap you can use a wet-vac and cover your nose with the free-hand.

#70250 Brent Wheel Won't Stay Stopped

Posted by perkolator on 19 November 2014 - 08:39 PM

yep, open the foot pedal via the bottom plastic plate.  inside there are two crews that control the stops of the potentiometer.  manual explains it much better.


if it was an issue of the wheel never stops or never starts - usually it's resulting after you drop the foot pedal - usual cause is either the plastic lever inside has somehow slipped off the potentiometer's lever arm, or the two plastic tabs on the main arm have broken off and no longer move the potentiometer.  I have both of this fault happen at least once a year on my Brent wheels.


this pic pretty much shows all the parts:


#68440 Clay That Can Be Used To Coat An Object Then Easily Chips Off Under Water Pre...

Posted by perkolator on 23 October 2014 - 01:10 PM

no, the different slips should not bleed into one another unless you layer them when they are sloppy wet - and in that case it should be pretty obvious when you're witnessing the previous color bleeding into the 2nd bucket while you dip.  simply dip the object, let it dry to around leather-hard or slightly wetter (at least enough to lose its glossy sheen), then dip your next layer(s) and repeat.  one layer should net you a thickness roughly 1/16" thick is my guess (on a non-porous object), but truly depends on viscosity of the slip.  you can also do multiple layers of each color so they're thicker if you need it.


the main reasons why i suggested food coloring is because the stains or oxides are pricey, but also because it sounds like you're going to be wasting the materials by hosing them off...and then you have the environmental factor depending on where your materials end up once hosed off.  clay materials should be fine to wash off into environment, but once you start adding in metallic oxides in concentration we're talking about something different.

#68427 Pictures Of Your Studio

Posted by perkolator on 23 October 2014 - 10:01 AM

As we all know, ceramics is heavy already, and when you make it life size, you have more complications with transport and storage (unless you build in sections like we encourage many to do). Also many undergrads aren't art majors, many move housing yearly, don't have vehicles, or maybe don't have space in their shared living situation that can accommodate a 6ft 200lb sculpture. We do keep some work for our sculpture garden every year if it's presentable to the public, but for the most part is up to students what happens with their artwork. Of course we encourage everyone to hold on to their work as long as possible, so you at least give it time to sink in and really gather personal thought and feedback, or if you even just keep a small piece that represents what you wanted from your failed attempt.

When it comes time to dispose of it, we encourage it gets broken up so that you will not find your own work included or claimed in somebody else's work, or so that if/when you become successful as an artist, you had a choice regarding what past work exists (ex: in case someone dumpster dove your work 20yrs ago when you were an undergrad and it now has value). I'm sure many people here regret giving away old junky pottery that doesn't represent you very well, but that's what they and the people they show it off to know you by...

I know it's a shame to toss so much beautiful (hopefully it wasn't) artwork every year, but in reality you can always make more. It's similar to when I do throwing demos in HS classes and they gasp when I chop up a freshly thrown pot (that would have taken them all class period to make) just so I can show them a cross section of what/how I just did...because you can make more :) Usually when you do continue working, your work improves as you progress.

To a certain degree it is better to make unsuccessful art and be unhappy when you open up a kiln - this is because if you're truly interested in the material, then you will have more desire to improve and take steps to not repeat, hence you learn exponentially faster. When you open your kiln and everything is successful, you have a tendency to stop forward progression because you're already getting what you wanted.

#68392 Pictures Of Your Studio

Posted by perkolator on 22 October 2014 - 06:13 PM

i'll share a few...sorry for big pics, it won't let me upload from the file sizes i have.

i'm very privileged with the studio that i get to run and maintain.  not really sure how i'm going to deal with the change when it comes time to pass the torch...


originally build as an army barracks in 1947


typical clay run, i do 2-3/year





#68387 Clay That Can Be Used To Coat An Object Then Easily Chips Off Under Water Pre...

Posted by perkolator on 22 October 2014 - 05:21 PM

i suggest casting slip.


try calling up some local ceramics suppliers (or even a ceramics studio) - you may have one that makes their own casting slip in large quantities.  if so, it's usually pretty cheap (compared to commercial slips) and sometimes you can buy it in 5-gal buckets if you're lucky.  


due to the properties of casting slip, i think this specific clay variation will be best for your application because it should really cling to the object and dries differently than your regular clay for throwing or sculpture.


also, since you want color variation and because you're not firing the material (and will likely get it all over the place with the water blasting) i would suggest you color the slip with something like food coloring.  personally, i'm colorblind and have many times used food coloring in my glazes so i can tell the difference when i'm glazing with multiple glazes.  food coloring simply burns out in kiln.

#67737 Is A Tie-Dye Effect Possible?

Posted by perkolator on 13 October 2014 - 04:56 PM

pics of the results?  i may have to do some testing now - just tie dyed 5 shirts this weekend, so now i need some matching ceramics!

#67430 Icing For Ceramic Gingerbread

Posted by perkolator on 07 October 2014 - 07:19 PM

try this:


Arnie's Fish Sauce Slip

43.6 Grolleg/China Clay/Kaolin

15.6 Silica
23.4 F-4/Minspar/soda spar
7.8 Pyrax/Pyrophyllite
9.5 Bentonite 


can be mixed super thick, like cream cheese thick.  have had students pipe it out with success.


‚Äčanother option would be a 2nd firing with white Egyptian paste as the icing.

#65930 Is A Tie-Dye Effect Possible?

Posted by perkolator on 10 September 2014 - 12:38 PM

What shape is your finished piece going to be?
For a flat surface I would tie dye a cloth using underglaze colors, then simply lay it on the piece and use a roller to smooth the colors onto the surface. Fire low, apply clear glaze and re fire.

This.  Use UG or raw stains/oxides for stronger color, and dye a piece of fabric.  stick it on a moist clay object and the colors will transfer to a certain degree.

  • Mug likes this

#52281 Clay Body For Large-Scale Project

Posted by perkolator on 12 February 2014 - 11:18 AM

Yes, Arneson used to build some thick, solid work. Our methods were pretty much initiated by him, and were passed to us through George Grant (he was tech for like 25yrs) and our Faculty who has also worked in thick, solid ceramics most of her career. We haven't changed a whole lot in our process and our firings still take 5-7 days before work can be unloaded due to the scale and method (also because in a 10wk quarter system makes challenges when working this big).

We don't have humidity issues here in CA, we're actually in a severe drought - so drying should be fine, if anything it would be too fast. With a high grog content on other porosity added to the clay body, the pieces will dry out even better at the core where it's most important.

The piece will be a big relief that starts with a base around 3-4" thick. It will likely get both carved and added to. Piece will get cut up and put on boards (or will already be cut into tiles beforehand) and then onto ware carts for drying. Whole cart will be under a plastic sheet to slow it down. Anything not fitting on the carts I'm going to have to rig up some sort of elevation system to get airflow under the work like Marcia mentioned with the sticks, only with multiple levels due to volume of work and because many carts will be occupied with student work. I don't like to push force drying too fast, but bringing the carts into the heated building will help, as will force drying in the kiln if need be. It'll likely take a month for the work to dry enough for firing is my guess.

Firing will be in downdraft gas kilns, fired over the period of perhaps a week and cooled over several days as well. With the thickness, it will likely need down-firing to keep from cracking in cooling. Individual pieces will be flat on the backside, so they will all get propped up on balls of kiln wadding (equal parts silica grog kaolin) when placed in the kiln.

This has all happened really fast and I dunno who's idea it was to at the last minute decide to have this huge ceramic piece/demo as part of the event. This is not really one of those things you take a last minute approach like this, but we're doing it. If anything, this will be a big, fun experiment with tons of clay! It will get lots of documentation, no worries there ;)

#51376 Price Of Fuel Slowing Anyone Down?

Posted by perkolator on 30 January 2014 - 04:18 PM

Kind of off-topic, but has to do with fuel prices....


Yesterday, Jeff Chown from Blaauw Kilns came to our class and did a powerpoint regarding the innovations in kiln firing tech that they are now implementing in industrial ceramics (since all of our current ceramics-related tech has been passed down to us from industry).  I was very surprised to see that with the way these kilns are being designed these days, energy/fuel consumption will be drastically reduced.  


Jeff gave some examples comparing old, updraft hard-brick kilns to the new fiber kilns and there was something like a ridiculous 75% fuel savings for the same firing results.  Some of these kilns in industry (depending on what's inside) can be fired (AND COOLED) in a 14hr period to ^10!!!!!  


I know that I personally will never be able to afford one of these beauties, but man has kiln tech come a LONG way in the past decade or two.  If you're looking for a serious way to save on fuel costs, cough up some dough in the beginning and watch the savings add up with each firing!


I'm still in amazement with what was presented to us...

#43667 Beehive Kiln?

Posted by perkolator on 03 October 2013 - 05:50 PM

Nearby my location we have Gladding McBean, where they have several beehive kilns that are still used for firing sewer pipes.  They are pretty big, maybe 25ft tall, 30-40ft diameter, downdraft kiln powered by 6-8 natural gas burners.  I believe they fire them up to around Cone 7 and it takes around 3wks (1wk preheat, 1wk firing, 1wk cooling).


here's our students going through the beehive kiln room/warehouse a few years ago when you could still tour the facility:

Attached File  photo (15).JPG   112.24KB   0 downloads

and one off the net:



#42055 Clay For Large Figurative Sculpture

Posted by perkolator on 04 September 2013 - 01:57 PM

based on what you've said, i think ANY sculpture body would work just fine in your application.  you will want something with a decent grog content (fired clay that's ground up) as opposed to something that's smooth, like a throwing body.  if you can find an architectural clay body, that would be even better for the large-scale items you want to make.  the fire clay we use is the base of our clay body because it's local to us and therefore very cheap - unless you are planning to make your own clay, which i'm assuming you're not, then i would recommend you call up your local ceramics suppliers and discuss with them your project to see what clays they stock.  i'm the ceramics lab tech for UCD.

#41991 Clay For Large Figurative Sculpture

Posted by perkolator on 03 September 2013 - 03:23 PM

kind of a loaded question.  depends on a few factors.  since you mention "water based clay" i'm assuming your experience is with oil based clays?  also, what are you considering "large scale"? (like life-size human figure sculpture?)  how are you planning to build? (armatures for support? solid or hollow forms?)  also, how fast are you building? 


students in my studio are typically producing large-scale sculpture (2-6ft tall, up to 1-2" thick).  we use a house-made stoneware body that's mostly Lincoln Fire Clay with 5-10% 20m grog content.  most sculptures are built in a week's time, always hollow forms with no support structure/armatures.  typical firing is to ^04 or ^5/6, usually once-fired over a 3-5 day schedule.