Clay That Can Be Used To Coat An Object Then Easily Chips Off Under Water Pressure

[MeganWolf]

For a senior design project, I am looking for a clay that I can dip an object into then pull out to produce an even coating.  After the initial layer hardens, I would then like to dip it and remove it from a clay of a different color.  I would also like for the clay to chip off when sprayed with pressurized water (a little more so than a garden hose).  The idea is to test the effectiveness of spray nozzles and we are hoping by having it chip off certain color clays in one area, we would be able to use image analysis to determine how many layers of clay and in what area the nozzle was able to spray off.  Any suggestions would be greatly appreciated.  Thank you for your time to answer this post.

Kind regards,

Megan

[Chris Campbell]

If you don't fire the clay then any clay body will come off under pressure from a water spray.

Just use different colors of clay in slip form and let it set up between color layers. By 'set up' I mean wait until the wet clay has lost its sheen before dipping the next color. You can build up a dozen of layers if you want.

Many potters use the hose spray to create layers of design on unfired pots.

[MeganWolf]

Thank you so much for taking the time to help Chris, you made designing my project a lot easier.  Is there a specific kind of clay that you would recommend and should I be concerned about the colors mixing together?  Thanks again for your help!

[Chris Campbell]

No special recommend. They should all do it.

Let each layer dry to the touch between dips and they won't mix together ... It's only if the previous one is still runny that they would mix. You can decrease this risk even more by doing thin coats of the same color to build up a thicker layer.

It should be fun to make and wash ... The same day if you are in a dry climate.

[Chilly]

Don't forget to post pictures, we love to know how things went.........

[perkolator]

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.

[MeganWolf]

Thank you so much for the wonderful suggestions!  Knowing that this idea is possible is making me more and more excited to start this project.  I cannot wait to share my findings and should be able to post pictures within the next 2 weeks.

 

Perkolator, thank you very much for your specific suggestion!  Do you think the food coloring from one layer would bleed into the color of another layer when it gets wet?  I did a little research and found that you can dye casting slip with Mason stains- would this be less or more likely to bleed into another color?

 

Again, thank you all for this fantastic advice!

[oldlady]

considering that the cost of Mason stains runs to over $30 a pound and food coloring is a little less, you might want to.............

[perkolator]

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.

[MeganWolf]

This is great information to know, I think I will go with the food dye which is readily available.  I also just made a few phone calls and a ceramics studio in the area does have their own casting slip.  Thank you for all of your suggestions!

[Tyler Miller]

Clay probably won't work for this application. I'm actually surprised no one's brought up shrinkage. The second your clay starts to dry, it will peel and flake because it's shrinking. I would suggest going to your local University's engineering dept and see what testing materials are commercially available. There IS a commercially available product for this application. The product you're looking for is like coloured chalk dust suspended in a water soluble binder.