Using Mason stains

[bwerkheiser]

Would like to start using Mason stains to make colored clay, specifically Amaco 38 white. Wondering if addition of stain affects firing composition of clay or if routine firing practices can be followed? Thank you 

[Min]

Hi and welcome to the forum.

In general ceramic body stains (Mason or other brands) are made to be used to colour porcelain. Like anything in ceramics when trying something new run some small tests first. I don't know how much you know about stains but there are a group of body stains formulated for adding to claybodies rather than glazes. Glaze stains can also be used for bodies but there are some that won't work well. Have a look at the Mason Reference Guide, stains with a number 1 beside them are suitable for body stains. Are you firing to cone 10?

Edited August 2, 2023 by Min
added link

[bwerkheiser]

Thank you for responding…sometimes difficult to get specific questions answered on-line. I was planning to fire at cone 6…. don’t have a personal kiln yet, but when I do, it will be electric, so I’ll be firing at cone 6. Will I have any potential problems with Amaco 38 colored with a Mason stain at 6? Also, I have no experience with stains. Thanks again for your reply.

[Min]

That clay has a posted 7% absorption rate when fired to cone 6 because it doesn’t mature until cone 10. This means it’s immature at cone 6 and will probably weep/leak. If you are making nonfunctional work it might not be an issue but the clay also won’t be as strong as a mature body.

[bwerkheiser]

If I cover the piece in 3 or 4 coats of clear glaze, won’t the piece (lets say a small bowl) be functional for light usage?  Also, do you know of a white clay that can fire at cone 6 and be mature enough for use as dinnerware? Thanks again for sharing your knowledge….I’m trying to soak up as much info as I can about ceramics, but I find so much contradictory material on the web. 

[PeterH]

3 hours ago, bwerkheiser said:

I was planning to fire at cone 6…. don’t have a personal kiln yet, but when I do, it will be electric, so I’ll be firing at cone 6.

Be aware that kilns advertised as cone 6 may have a short element life if regularly fired to cone 6.

In https://community.ceramicartsdaily.org/topic/30261-paragon-dtc-800-kiln/?do=findComment&comment=228238
A cone 6 kiln firing to cone 6 will only get maybe 50 firings before the elements need to be replaced. Once they wear even a little bit, the kiln can no longer reach its max temp. In a cone 10 kiln firing to cone 6, the elements can wear a lot more before they need to be replaced. If your cone 6 kiln is getting more firings that that, then it is probably under-rated.

 

[Min]

4 hours ago, bwerkheiser said:

If I cover the piece in 3 or 4 coats of clear glaze, won’t the piece (lets say a small bowl) be functional for light usage?

If the base or foot of the pot is not glazed (usual practice for cone 6) then water is going to get into the claybody very easily through doing the washing up. When moisture gets into the claybody and the pot is heated it will cause the moisture within the clay to expand which in turn will craze the glaze. (it also makes the pot get extremely hot if microwaved) It's easy for oils, liquids etc to get into the porous body via the unglazed portions and the craze lines and go rancid if the clay isn't vitrified. 

If you will be firing to cone 6 then look for a body that has less than 2% (or even 1.5%) absorption. I don't live in your part of the world I so can't make a personal recommendation on what is available where you are.  You could post a question asking for recommendations. @Pres, I think you are in the same area as the OP, do you have any you could recommend?

Edited August 3, 2023 by Min
grammar and added a thought

[bwerkheiser]

Thanks again for the feedback. My intention is to make stoneware mugs, bowls and plates that are food-safe, but I want to fire at cone 6.  So, I’ll start looking for a clay body that can fire at cone 6, but has a low absorption rating. Also, on a different topic from a year ago, I read that someone recommended applying a food-safe epoxy to the unglazed parts of the foot after firing to seal the piece. Is that possible?

[bwerkheiser]

PeterH, wanted to thank you for the kiln information….it certainly gives me something to think about before I make a kiln purchase.

[PeterH]

6 hours ago, bwerkheiser said:

... something to think about before I make a kiln purchase.

Lots of good stuff by the experts over in the Equipment Use and Repair  forum. Especially if you are considering a second-hand kiln.

[Callie Beller Diesel]

16 hours ago, bwerkheiser said:

I read that someone recommended applying a food-safe epoxy to the unglazed parts of the foot after firing to seal the piece.

While it’s possible, it isn’t common practice, nor is it economical. It’s less work to fire your clay to maturity if you’re using stoneware or porcelain of any kind, or to fully glaze all surfaces if you’re working with earthenware. 

If you’re just trying to fix a mug you made for yourself that you’re proud of and that isn’t leaving your house, it’s probably fine. If you’re selling at any scale, even just a couple of mugs on Etsy, I wouldn’t. It’s not good workmanship. 

[bwerkheiser]

Thank you for your reply….this helps put things in perspective for me. So it looks like firing at cone 10 is somewhere in the future.

[Hulk]

There are many clay choices that mature at cone 5/6 with very low absorption.

[Callie Beller Diesel]

When I google PA clay manufacturers, Standard comes up as one of the first ones, and several forum members here use that brand. Hopefully one of them chimes in. They have a big ‘ol list of cone 6 clays here, with about 7 options that have 1.5% porosity or less* and are some shade of white. They also appear to sell some kinds by the dry bag, which would be very useful for making coloured clay with, if you want more than just a yogurt container full for decorating. On the Standard distributor page, there’s a place called R.I.CH  Inc in Bernville and The Ceramic Shop in Norristown that seem to be the closest to Easton.

If accessing cone 10 firings is an issue, and it can be for some, there are options. If you have easy access to a gas kiln, never mind the above and carry on. 

Amaco is great for bottled glazes and underglazes, but their clay selections seem to be geared towards teaching scenarios where final porosity isn’t a primary concern. It also seems to run a few dollars more than some of the ones from other suppliers.

*whichever clay body you go with, you should do a porosity test under your own firing conditions to verify claims made by any manufacturer. You may be doing something different than they did for their tests.