*insert witty title here*

August 22, 2012 8:41 AM

Can anyone help a glazing (pottery, not cinnamon buns) newbie find or formulate a glaze recipe that will match our existing dishes?

TL;DR at the bottom. Details, context, and additional tip requests in between.

So the missus and I have been taking some pottery classes over the summer and I'm looking forward to sticking with it for a while. I'm getting decent on the wheel and glazing isn't as much of a mystery as it once was. Anyway...

A cool mini-project that I'd like to tackle would involves crafting a replacement lid for the Harkerware china set we inherited from MrsEld's grandmother since ours is currently broken/repaired.

I haven't actually made any lids yet but I figure the tactile/technique aspect of throwing it will come with time and/or instruction from the teacher.

I have full access to a art center that keeps about 16-20 five gallon buckets of various glaze formulas ready to go at any given moment but they also have bins and bins and bins and tubs and jars of powders/underglazes/etc that are also available. For what it's worth none of their pre-prepared glaze mixes, that I've used or seen others use at least, seem to be as vibrant as this harkerware yellow glaze is so I wonder if it's something different altogether. I'm assuming the staff could help me with setting up/mixing whatever I'd need if I asked nicely enough, they seem super helpful...

I'm unsure as to what temp their kilns fire at but I can ask, and perhaps even request a special temp/cone for certain things outside their normal bisque and glaze fire temps/runs.

My clay type is probably limited to what they have on hand (6 options or so, one being recycled), but I can talk to the staff there and do test runs to see what works best for my needs.

I'm sure the staff could help me but if anyone happens to 'know' or have experience regarding this kind of thing I'd like to go in with info to help them help me, if you know what I mean.

TL:DR:
Can you help me with the recipie to match the glaze pictured on this creamer so that I can craft a replacement for the lid of this sugar caddy?

posted by RolandOfEld to sports, hobbies, & recreation (14 answers total)

I forgot to mention: Of course the trivial solution is to buy a replacement on ebay/etsy/whatever. Please discard the trivial solution. Bonus points for 'showing your work' so that I can maybe learn something about how glaze formulae actually work.

Thanks.
posted by RolandOfEld at 8:45 AM on August 22, 2012

It's critical to know if they fire to cone 6 or cone 10 -- the glazes for the two ranges are completely different. If they're firing electric, then it is probably cone 6 -- most cone 10 firings are in gas kilns.

I throw a lot, but I don't mix the glazes (but my friend does). Looking at the piece you want to emulate, it's almost certainly a low-fire (cone 6) glaze. The yellow interior looks to be a commercial underglaze. Check out highwaterclays.com and they have a good selection of commercial stuff. Beyond that, you're just better off searching online (or reading ceramics monthly back issues) for low fire glaze recipes, mixing them yourself, and doing TONS of test tiles. Be warned though: most group studios don't like people to just go off glaze mixing with out abandon, so you *must* check with your studio manager before putting a foreign glaze/clay body into a kiln (esp with other people's work!)

Have fun!
posted by virga at 8:58 AM on August 22, 2012

I think you might want to start by asking your technician or teacher whether this is something you would be able to do there. I've been throwing for about a year and a half and have taken classes at several different studios, and I haven't encountered any that allow casual students to formulate their own glazes. (This is why I don't know anything about mixing glaze yet myself!)

On preview, virga's note that the interior looks like commercial underglaze is a thought worth pursuing. I definitely have seen students bringing their own commercial underglazes into the studio; so if you have a good clear glaze on hand, which you probably do, painting with a yellow underglaze and then glazing clear might be a good option for you.

And finally, the Ceramic Arts Daily forums would also be a good place to ask this question, if you do discover that you're allowed to fire glazes you've mixed yourself.
posted by snorkmaiden at 9:04 AM on August 22, 2012 [1 favorite]

Is it porcelain, a whole different category altogether? Bring it in to show your teachers.
posted by mareli at 9:08 AM on August 22, 2012

virga:
Cone 6 sounds right for what we've been glazing at in class. The kilns (they have multiple, perhaps dedicated?, ones) are electric.

Regarding checking with a manager, yep will do, wouldn't even consider skipping that stage.

snorkmaiden:
I've seen the Ceramic Arts Daily front page before and enjoyed their videos, will check out the forums. I've also asked the teachers and I think this is something they deal with on a case by case basis, but I got the impression that if you're taking classes then anything, within reason and time constraints (mine and theirs), is fair game. I guess if it REQUIRED making a large, not small, batch of 'Roland's Yellow' then it might be a problem, I haven't considered a small batch being a non-starter but figured they would have told me.

mareli:
I have no idea, but will be bringing in the piece once we're back in session.

All:
The underglaze idea sounds promising. Although I've yet to mess with underglaze yet I'm vaguely aware of what it is and how it's applied. Hrmm...
posted by RolandOfEld at 9:12 AM on August 22, 2012

Making your own glazes involves working with messy, toxic, expensive materials. They might not let you do this.

Visiting a ceramics supply place will let you look at hundreds of samples of commercial glazes. It's inexpensive to buy a small bottle of one or two. I'd recommend you go that route.

You might also consider if this should be a food-safe glaze. Use proper precautions for applying lead glazes. Wear gloves.

Glazes are tricky and mysterious. If you want to learn to make your own, starting with a goal of getting something to match is going to be frustrating. Be sure to wear a cartridge respirator if you are going to work with powdered materials, they are more expensive than the disposable masks but significantly cheaper than a new set of lungs.
posted by yohko at 10:15 AM on August 22, 2012

Just looked at the pictures... I think I have something I did with a commercial glaze that is that color of yellow.
posted by yohko at 10:16 AM on August 22, 2012

Former glaze chemist here. As yohko said matching is one of the hardest practices to get right. You need three big things and all their component parts to go just right.

1. The right clay, if you are not using the same clay as the original forget about a color/texture match.

2. The right recipe made with the right ingredients there are a lot of approaches to what would otherwise be the same chemical equation using different feldspars etc that will change your mix.

3. The right firing. same heat, over the same time, with the same pace of warming and cooling and the same introduction/exclusion of oxygen.

If you go 3 for 3 then you're good. My Final project for my degree was matching a particular copper red, which took the better part of a year to get right.

However it can be a lot of fun to try I'm just painting a picture of what you're undertaking not trying to talk you out of it. Talking to a commercial manufacturer/glaze store nerd will be both fun and educational if you're interested and will get you a good match. It might be a better place to begin. Buy that glaze and then tinker with some simple glazes of your own.

I recommend cobalt blues as a nice satisfying place to start.

Although a good teacher would likely say start with whites to get a sense of melt, run, sheen and texture first. but that's no fun :)
posted by French Fry at 10:34 AM on August 22, 2012

yohko:
Fair points and well received. I've no idea what amount of PITA factor to expect with mixing glazes, I figured it was as simple as mixing solids, liquids, keeping dust down, ventilation up, and perhaps wearing a mask/respirator as needed. If it's much beyond that then I'll focus on finding a commercial solution.

Have any idea what commercial glaze you think might be a match or close match? Or I guess without having matching clay types it's a futile exercise.

French Fry:
Great tips, thanks.
posted by RolandOfEld at 10:43 AM on August 22, 2012

Yeah, there's a ton of variables there, and without seeing the piece in person, it's going to be pretty much impossible to tell you exactly how to match the original. And even after someone gives you advice in person, you're going to have to do a great deal of testing to come up with a match.

But, just to throw it out there as a (possibly simpler) option: mason stains can be used with base glazes (usually a type of clear) in variable amounts to produce different intensities of color. They can also be mixed with each other to produce new shades, just like you'd mix paint.

As you and others noted, the first step is matching the color, feel, and "hardness" of the bare clay on your original to a clay body. An experienced ceramicist can likely tell with a tactile inspection whether the clay has been fired to a low (say, cone 04), mid (say, cone 06), or high (say, cone 10) temperature, and that'll be your starting point for finding the right clay body.

Once you find a clay body that matches your original when fired, you can then find a base glaze that gives you the texture and "feel" of the original's yellow-glazed area, and then mess with mason stain as a colorant that'll give you the exact shade.

One benefit of using mason stains is that you can add the stain to almost any type of base glaze -- cone 6, cone 04, cone 10, crackle, runny, matte, it doesn't matter. It's a lot more difficult to reverse engineer a cone 10 glaze that's the right color and texture to a cone 6 glaze with the exact same color and texture than it is to just start over with a new base specifically formulated for a different firing temp.
posted by lesli212 at 11:02 AM on August 22, 2012

Err drr, I meant to write "cone 6" for a midfire example, not cone 06. THAT'S A VERY IMPORTANT DIFFERENCE!
posted by lesli212 at 11:04 AM on August 22, 2012

A friend of mine does a lot of work at a local ceramics studio and has done a lot of experimentation with glazes trying to get thing just so. The things that frustrated him were variations between firings (most notably where in the kiln a thing was placed, but there were other variables) and people who kind of vaguely almost followed the recipe for the various glazes that they were supposed to be preparing (so that he never knew what he was really starting with).

Having done a bunch of analytical chemistry and handled some pretty toxic stuff, I can say that accurately mixing small volumes of solution is a lot easier and safer than mixing small volumes of dry powder.
posted by Kid Charlemagne at 11:12 AM on August 22, 2012

perhaps wearing a mask/respirator as needed

!!!

Oh dear, I forgot that I had taken my ceramics classes almost exclusively with people who had some experience with lab techniques. Please learn about proper safety measures if you are going to do this. Art materials are not the benign things many people think of them as.

It's really not too much of a PITA if you can be precise about weighing and measuring, the thing is just that you are unlikely to get as consistent a color and texture as a commercial glaze. If you don't care so much about what the end product is experimenting can be a lot of fun.

Please watch out for your safety though, and be aware of any other people you might be exposing to toxic materials from your clothing, etc. especially if you have kids I'm not saying you're going to be killed off right away, but silica dust and heavy metals are cumulative in their effects.

If the studio does let inexperienced people mix glazes, you might give some thought to what sort of safety precautions they are taking in general and think about if it's really the place for you.

/safety soapbox mode off
posted by yohko at 4:02 PM on August 22, 2012

I'm just dropping in to say that French Fry speaks truth and said exactly what I would have said. Heed him well.
posted by 1f2frfbf at 5:13 PM on August 24, 2012