boiling in milk to fix cracks in emile henry dish?
i heard that boiling porcelain in milk will repair hairline fractures. i have an emile henry earthenware baking dish that has developed some apparent hairline fractures (line on inside, but not on the outside.) this is like my dish: http://www.emilehenry.com/pages/produ...
will boiling in milk repair these cracks? what can i do to fix the cracks, if anything?
is it safe to use the dish if i don't "fix" the cracks? is the dish more prone to having a violent end in the oven?
It's probably 'crazing' in the glaze, which is very common with earthenware and old porcelain - basically the glaze is melted glass (and other chemicals and pigments) and crazing is fine hairline cracks in the top glass layer. Boiling a glazed vessel in milk will not remelt the glaze to eliminate the cracks--perhaps the milk protiens fill the cracks so they appear to be fixed, but that would only be superficial. Crazing often happens as a result of washing such dishes in the dishwasher, but sometimes it occurs in the firing process. There is nothing you can do to fix the cracks.
It is perfectly safe to use such vessels, assuming the cracks are really just crazed glaze and are not cracks in the earthenware itself. If the earthenware body is cracked, don't use them in the oven, they may leak or worse, meet that violent end.
The concern with cracked glaze is whether there is lead in the glaze. If you have any concerns about chemicals leaching from the crazed glaze you could set your mind at rest and do a test for lead in the glaze, but I seriously doubt that Emile Henry ware would have lead-based glazes.
I have the same Emile Henry dish and just used it for the second time (got it over the summer)- It developed a fine hairline crack but it went through to the other unglazed side. I've been using enameled le creuset oval au gratin for fish, chicken, roasting vegetables and frankly, love it! The clean up is amazingly simple and everything has cooked so well- I dont have to worry about these cracks either.
Years ago, when I bought my first piece of Emile Henry, the instructions told the owner to boil milk in the dish before the first use. I did this thinking it pretty odd.
I washed the dish but no matter what I did, there was a lingering smell of spoiled milk. After several washings, I returned the dish to W-S. They took it back without question, giving me another dish.
This time, I noticed the instructions about milk boiling were absent. All I did was wash the dish and have been happily using it ever since.
I cannot answer any of your questions about fixing your hairline cracks, but find it odd that this milk boiling idea persists. Anybody knkow how/why it began? any science to back it up?
I've worked a bit with ceramic glazes, glass (hot, warm & cold) and enamels on metal. I can think of no reason why this would work. To re-melt the glaze you would have to get to a much, much higher temperature than that. Nothing else will really reconnect the glaze.
To prepare a new donabe (Japanese clay pot) for cooking, it is traditional to cook a small amount of rice to both season the inside surface and I believe, seal hairline cracks. One website suggested using a couple tablespoons of flour as a substitute for the rice. Cook over low heat for an hour. Rinse and dry.
Emile Henry does recommend the milk treatment, but as far as I know it's only for their Flame Top line and it's to 'season' the piece before it's first use. It's only done once. They tell you to expect crazing in that finish. The other dish you show is a totally different line, and that should not craze. I would contact EH for warranty replacement on the dish.