Best clay for coasters?

[Bam2015]

Hi All,

I'd like to make some coasters and wondering if there is a 'better' type of clay that I should use. I want them to be absorbent so I would not be glazing them. I want them to soak up condensation. 

Thank you,

Betty

[Bill Kielb]

Hmm, I am not sure porous is a good idea as the water will go through them and potentially damage the table beneath. I have always made them non absorbent and added a silicone rubber backing to prevent slipping, sliding, scratching but still all be very food grade and washable. It would seem absorbent coasters would leave a ring. Just thinking ……

[Russ]

Ive used a high fire stoneware or porcelain with very fine grog- bisque fired only and then some cork backing to prevent moisture from reaching furniture.

[Bam2015]

2 hours ago, Bill Kielb said:

Hmm, I am not sure porous is a good idea as the water will go through them and potentially damage the table beneath. I have always made them non absorbent and added a silicone rubber backing to prevent slipping, sliding, scratching but still all be very food grade and washable. It would seem absorbent coasters would leave a ring. Just thinking ……

Yes, I hear what you are saying Bill, but I plan to use a backing to prevent table damage. 

Betty

Edited July 23, 2022 by Bam2015

[Bam2015]

1 hour ago, Russ said:

Ive used a high fire stoneware or porcelain with very fine grog- bisque fired only and then some cork backing to prevent moisture from reaching furniture.

Thank you Russ. I think a cork backing would be a good idea. 

I have mid range stoneware and porcelain, so I'll try those. 

Betty

[neilestrick]

I use low fire clay so that it's porous, but any bisque-fired clay would work. I make them somewhat thick, like 1/2" so they can soak up a lot of water, and put little rubber or cork bumpers on the bottom to protect the table from scratches. A full cork pad would also work. I've never had one soak through. The problem with non-porous coasters is that in a humid environment like the midwest where I live, the cup will sweat and leave a big puddle on the coaster, which will then either drip all over when you pick up the cup, or cause the coaster to stick the cup and then fall off at some point when you lift the cup.

[Roberta12]

I have made some coasters rather like I made brown sugar savers.  I use porous clay and take it to bisque temp.  On coasters I put cork backing.

r.

[Bill Kielb]

Unglazed bisqued clay seems pretty fragile to me. Maybe glaze and vitrify as normal and glue cork as an insert on top to get rid of the cup stuck to the coaster issue. Still thinking …….

[Rae Reich]

Cone 06 clay, fired to temp, is still porous enough for coasters. Non-porous bottoms are essential. A texture or shallow design on the upper surface will impede sticking to the vessel. 

[Bill Kielb]

5 hours ago, Rae Reich said:

 

Cone 06 clay, fired to temp, is still porous enough for coasters. Non-porous bottoms are essential. A texture or shallow design on the upper surface will impede sticking to the vessel. 

 

Maybe just glaze the bottoms and sides, texture the top. Fire up side down.  Nice!

Edited July 24, 2022 by Bill Kielb

[LeeU]

3 hours ago, Bill Kielb said:

Maybe just glaze the bottoms and sides, texture the top. Fire up side down.  Nice!

Now you've got me thinking I could use some coasters for myself! I have a nice groggy clay in mind.  I like the idea of glazing the bottom/side and having a nice recessed texture on top (perfect for good wood stamps).  I would design the glazed "bottom" so that I could glue on some very small furniture-protective rounds, and they would fit in with the design.  Thx for the motivation-boost.