I need a way to etch the glaze finish from a porcelain spot plate. Anyone have any idea the best way to accomplish this? Here is the plate I need to
etch.
[Edited on 17-9-2013 by sonogashira]hyfalcon - 17-9-2013 at 13:43
Thank you. I was hoping to avoid that chemical but everything is pointing me in that direction.
Would just using dilute HF in the cavity on the spot plate do what I'm needing to do? I just need the glaze gone and not the porcelain underneath.
[Edited on 17-9-2013 by hyfalcon]papaya - 17-9-2013 at 13:55
What about NaOH melt ?hyfalcon - 17-9-2013 at 15:30
Getting that whole thing up to that temp and keeping it there while melted isn't my idea of a fun date either.Bot0nist - 17-9-2013 at 15:49
The fired glaze is akin to glass. If you want to avoid using HF(aq), perhaps try a solution of ammonium bifloride. IIRC, it is a slightly safer way to
etch glass than HF(aq). Still, use caution.Mailinmypocket - 17-9-2013 at 16:02
Saturated ammonium bifluoride (~40%) works quite well. As the Botanist said though, be careful. A solution of this strength has etched glass within 1
minute in my experience. I have had good results by using saturated paper towel (w/ 40% aq ammonium bifluoride) on the areas to be etched. This etched
glass within minutes, for porcelain I am not sure but it must be close, experiment.
Here is a microscope slide that was exposed to ammonium bifluoride @40%. It was etched very quickly. On the glassy porcelain surface I would expect
the same.
[Edited on 18-9-2013 by Mailinmypocket]hyfalcon - 17-9-2013 at 16:07
I need to etch it down to the porcelain underneath. I'll give that one a go. What do you store the solution in? HDPE?PHILOU Zrealone - 18-9-2013 at 04:14
Maybe let some NaOH prills into it and allow air humidity to melt those at ambiant temperature...
Then it is only a matter of patience if you don't want to heat NaOH to speed up things...After a week or so...you should have porcelain etched.
I think that Na2CO3 fused can also be used as a glass etcher because of its basicity and it enters the composition of glass so it dissolves a bit into the glass layer (like likes like) and after washing with
warm water some of the glazing must be etched MrHomeScientist - 18-9-2013 at 06:00
Maybe let some NaOH prills into it and allow air humidity to melt those at ambiant temperature...
Then it is only a matter of patience if you don't want to heat NaOH to speed up things...After a week or so...you should have porcelain etched.
Just to clarify, when solid NaOH appears to liquify when left out exposed to air, it isn't actually melting. It is deliquescant - it ends up
dissolving in the water is absorbs from the air to form a very concentrated solution. This reacts quite differently than actual molten hydroxide,
which is melted at high temperature.
Your second point, though, is probably correct. Leaving such a saturated solution to sit for a long time would likely lead to some etching. I've never
thought of etching porcelain glaze though, so it'd be interesting to see what happens.
so it dissolves a bit into the glass layer (like likes like) and after washing with
warm water some of the glazing must be etched 
