I could see a few good reasons for this.
1) Easier to apply a good even coat of porcelain that is less likely to chip. I would bet that most people also don't clean them well enough and they don't want to deal with it.
2) You have less people complaining that you are making knock offs of vintage kettles in rare colors because the vintage kettles are already very difficult to find in relatively unused condition.
Either way I would recommend being a fan or subscribing to their Facebook page because they frequently post project photos of Webers, vintage stoves, Coleman gear, and more that is pretty darn cool.
I have dreamed of getting a Ranch done, but the wife would murder me because I am sure it wouldn't be cheap at all. I have heard the GAs and SJs have been in the neighborhood of $300 to $500 plus the cost of the kettle. If I had to buy a new Ranch with it I could buy a car cheaper lol.
I think I read a post by Independence Porcelain they requires that Webers be new/unused for the them to porcelain coat them.
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