I use etch all too. Takes about 8 min. I pat on an even layer and have gotten an even etch. Good luck

Thanks Trish and Kay for  your responses.  I do have sanding sponges but never tried them on my surfaces so I'll give them a try.  And the Etch All I've used is the liquid dipping version, although I do have a jar of the cream somewhere.  Maybe the cream will give me more of the results I'm expecting.

Etchall does have a shelf life.  I have been told that storing it in a cool place extends its etching ability. So if your etch is old or is stored anywhere where it is hotter, especially in the summer, its etching ability can be decreased substantially.  For this reason, I date my container of Etchall when I buy new one.  Also, etching larger pieces will take a noticeably longer time because of the significant increase of surface area being etched.  Make sure you occasionally agitate the etch so that the liquid that is at the interface of the acid and the surface keeps circulating and the strength of the etch is not depleted at that point. For this same reason, I sometimes remove a larger piece from the liquid Etchall, rinse or scrub off the off the cloudy surface with a toothbrush, dry it, and then place it in the etch again.   I also use Etchall etching cream for larger plates and vessels and scrape it off mid-etch and re-apply new. Same idea. (I don't throw that away, I just keep an extra container of Etchall cream that is not as "new " as the rest...it is still very usable re-cycled, just not quite as strong as fresh out of the bottle. Some people who do smaller pieces tell me they just mix it all back it together and it does not seem to affect the strength of the etch for repeated use.)   

    I agree with the previous posts...using different grits of diamond sponges lends some delicate matte finishes which I use on jewelry and smaller pieces. However, I have found that they are not practical for getting matte surfaces on much larger pieces or pieces with a lot of concave tight surfaces. I am sure there are many suppliers for this product including Rio Grande but I now get mine from Coral at Enamelworks Supply.  I am then supporting the enamel community instead of some larger company that manufactures abrasives.

    As an aside, unleaded enamels have a much higher degree of acid resistance.  Using leaded enamels greatly increases your etching ability.  However, there are a few exceptions to this rule, i.e. 1010 Unleaded Opaque White which etches quite readily. I have achieved a beautifully even etch (like an eggshell), ready for drawing with ceramic or graphite pencils by placing a piece of copper with a mature, high fired surface of 1010 in clean hot pickle. (Heat accelerates chemical reactions such as this.)

    I used to use Armour Etch years ago but have now removed it completely from my studio and from all the workshops that I teach. Although it is less expensive, it contains hydrofluoric acid which is significantly more harmful, even in small amounts than the ammonium biflouride in Etchall. Because I etch a lot, it all adds up, for me. (Regardless of what product you use, always use gloves when handling etchants.)  I have found Etchall to be cost efficient because it can be used again many times before it is depleted, which Armour Etch does not lend itself to so readily.

   I am sure there are other etching methods and opinions. This is just what works for me. 

I etch my lamp work beads for a matte surface with liquid Etch-All Dip'N Etch and it takes about four minutes for a nice even etch.  I was surprised how much longer it took to etch some of my enamel pieces--about 45 minutes or so.  So I'm wondering how long you leave your etchant on the surface and if you have a favorite brand.  I know there's another one called Vari-Etch Frosting Powder that mixes with water and I might try.  Speed isn't really an issue for me but the quality and consistency of the final surface is.    Also, do some enamels etch more easily/evenly than others?  I know with lamp work glass some types (manufacturers, coefficients, transparents/opaques/colors, etc) are more resistant to etching products and can result in an uneven surface.  Thanks in advance.  Mary