ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Important Considerations in Ceramic Construction

Updated on February 8, 2020

Design Considerations for the Ceramic Room Heater

We begin by looking at what is necessary to make this project so that it is safe to use and functions as intended. As a result of plenty of experimentation, the author has determined that certain minimal requirements must be met.These include;

  • Knowing the shrinkage of the medium between wet and final firing
  • The right size
  • Limits of the material
  • Where it is to be used

This is the candle powered terracotta   heater at the focus of this instructional article.
This is the candle powered terracotta heater at the focus of this instructional article. | Source

Considerations For the Proper Size

Given the fact that any clay will shrink from the initial wet state to the final firing, we need to know how to size the piece so that it ends up at the correct size when fired. After more than a year of experimentation, it has been determined that the ideal size for the four candle ceramic heater is 6 inches tall and 5.5 to 6 inches in diameter. This is the final size. So, just how much larger do you have to make it it the initial stage? That can be determined by making a test strip before you even begin making the project.

The test strip needs to be made of the same clay type as your piece. All clay that you will be using, sould be wedged to drive out any air bubbles. The test strip should ideally be as thick as you clay wall in your piece. Make it of a length that is of some easily divided number like 5 centimeters. Mark the dimension on the piece while wet. Making it any bigger could be a little cumbersome and possibly too fragile.. Dry and fire the piece and measure it again. You will notice that the fired dimension is smaller than the wet dimension. That difference is the shrinkage of the clay body.

Dtermining the Amount of Shrinkage for a Clsay Body

Calculating the Project Size From the Test Strip

Once you have the fired test strip that is marked with the wet length, you are set to remeasure the fired strip. You will find it shorter than the marked wet length. Note the new length and compare that with the wet length you recorded before drying and firing. In a factitious example, say your wet length was 5 centimeters (50 millimeters) and the new measured length of the new fired length is 45 millimeters. The difference is 5 millimeters. A little quick math tells us that the test strip has shrunk by 10 percent. Your results will differ.Terracotta tends to shrink the least and porcelain shrinks the most.

Now, in this factitious example, you have a test strip that is 90 percent of the wet dimension in length. What you want to do now is divide the old length by 9 and take the result (approximately. 5.55 millimeters) Add that to the wet length. This is the guide to working larger than the finished fired size to be,

For a piece that ends up at 6 inches tall and 5,5 inches wide, you will need to make it 6.6 inches tall and 6.05 inches wide when made from wet and plastic throwing clay. Now your test strip may be different, so you will have to make your own calculations, For the terracotta used by the author, the shrik rate was 12 percent. Yours will likely differ depending on included materials that are used to increase shock resistance and reduce shrinkage.

Understanding Limits of Your Medium

Like anything else, there are limits which must be understood in order to get the most out of your project while being safe. The ceramic candle powered heater must be the correct size and of the right clay. Not all clay types are suitable. Choose a high grogged clay for maximum shock resistance and durability. A high grogged clay will not shrink as much as a non-grogged clay when fired. Do not make the top part (the bell) too small or too large. A top that's too squat and small is a fire hazard. One that is too large is inefficient and will not heat properly. Experiments have determined that a size of six inches tall is close to being optional with the least risk. The walls should not be too thin or too thick. They should be formed thick enough for you to decorate and add heat transfer vanes.

You might wish to vary the form, but bear in mind that the end result should be self supporting and not top heavy or unbalanced.

Use a clay with as low a shrink rate as possible. This lessens thermal shock. A high shrink rate clay may result in shattering when on use; a highly dangerous situation. A bisqued top is better for the pyrpose intended than a vitrified top.

Considerations as to What Clay For USe

Here is a situation where one size fits all does not fit!. There is a huge variety of clay types for various purposes. The main groups are terracotta, earthenware, stoneware and porcelain. Each one has a specific range of uses. For instance, you cannot use terracotta for making a substrate for a crystalline glaze. Nor can you get away with making a piece of varying thickness using porcelain. Stoneware is the best type of clay body that you can use to make ovenware and cooking. Earthenware, due to a huge variety of glazes available at low firing temperatures is excellent for many art projects for all ages. The use of terracotta is ideal for what is being considered by way of a low temperature, shock proof, heating appliance. It is also ideal for making coolers of various types. We will look at cooling applications in a separate article.

When making your terracotta heater, you will be firing the top, bell shaped part to bisque firing of about cone 06 (1,828-1,855 deg. F). The kiln atmosphere will be glowing orange in color at maximum firing. Some kilns use a kiln sitter with a small cone that shuts off the kiln when the right temperature is reached. The bottom dish will be glaze fired to about cone 02 with a clear glaze after bisqueing. The top part is fired only once and the bottom part is fired twice. This is because the bottom will be glazed after a bisque firing and then refired.


This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

Show Details
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
ClickscoThis is a data management platform studying reader behavior (Privacy Policy)