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<p>[QUOTE=&quot;Taupou, post: 2793137, member: 45&quot;]There is often a confusion in discussing pottery, since potters may use different terminology than collectors or the general public.&nbsp; Plus additional problems may develop when discussions include those whose native language is not English.&nbsp; So I am &quot;speaking&quot; here as both a potter, and as someone who is used to American English.&nbsp; </p><p><br /></p><p>Some of the posts do not use terms a potter would use.&nbsp; I assume &quot;glaze&quot; is what was meant,&nbsp; rather than &quot;enamel,&quot; for example.&nbsp; And this was thrown on &quot;potter&#039;s wheel, not made on a &quot;lathe.&quot;</p><p><br /></p><p>The small dark spots and burst bubbles are commonly called &quot;pinholes,&quot; or &quot;pitting,&quot;and are a result of the chemical reaction of tiny bubbles of gases escaping from the boiling glaze during the firing.&nbsp; The bubbles can happen anywhere within the glaze, or on the surface, where they may have burst, leaving sharp edges&nbsp; </p><p><br /></p><p>A crackle glaze can be deliberately created, or can be a defective result of the formula of the glaze not being designed for the particular clay body, causing them to shrink at different rates. And it can occur during firing, or slowly, at any time over the life of the pot.</p><p><br /></p><p>Pin holes or crackling can also be a result of not being correctly fired.&nbsp; The kiln may have not been fired to the right temperature, it may not have been fired long enough, or held at a particular temperature for long enough.&nbsp; It may have cooled too fast.&nbsp; Whole books have been devoted to this sort of problem, so it can&#039;t really be solved here.&nbsp; This pot probably dates to a time before the emphasis on studying chemistry and science in connection with making pottery, was even considered.</p><p><br /></p><p>All these things can be purposely created to make a pot look older than it is, especially if it is buried in dirt for some time, and then cleaned up.&nbsp; Not saying that&#039;s what happened here, only that it is possible to reproduce all those effects.&nbsp; Just something to be aware of, and why determining age from a photo is sometimes difficult.&nbsp; </p><p><br /></p><p>One other thing, cobalt, which produces the blue, has been used on glazed pottery since at least the 7th century in China, 9th century in the Middle East, and long before a Swedish chemist &quot;discovered&quot; it in 1735.&nbsp; It may not have been called Cobalt, but it was a result of that same ingredient being used.[/QUOTE]</p><p><br /></p>

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