Clear Glaze over Glaze

[LCFAYA]

Hi, this might sound weird but I can't find anything related to the following. I am glazing cups and using on the inside different Amaco PC glazes. I did some carving and chattering on the outside, so I am planning on applying one coat of the same glaze I used on the inside with a brush on the outside, but very thin and even take some of it out with a towel to show the carving effects. I was planning then to dip the outside in clear glaze (HF-10) to protect it. Has someone done this? Are the glaze colors going to react with the clear glaze?

Thanks a lot for any comments or suggestions

Luis    

[Gabby]

I have overlapped clear over the Amaco Potters Choice kind of accidentally and found it does interact with the glaze.

If you love these cups, you might want to explore what might happen by trying it on test tiles rather than sacrifices your cups.

[neilestrick]

A clear glaze will react with other glazes just like other glazes do- it will mix and mingle and affect the first glaze. It doesn't just sit on top. How it will react will depend on the formula of both glazes. Best to test it first. If your clay is vitrified, then there's no need to put a layer over the top unless you don't like the roughness of the raw clay.

[LCFAYA]

That's was my main worry, that the clear glaze was going to interact with the base glaze and change the color. I should test, but... time is limited.

Cups are made of porcelain so once fired the texture on the outside will hopefully be ok  without the clear glaze. I liked the CG finish since they are easier to clean.

Thanks for the help. 

[JohnnyK]

Welcome to the Forum, Luis. Testing is the best way to go as Gabby says, but you should note that when you do thin coats of the PC glazes, the colors that you finish with may not be what you started with.

[Gabby]

What Johnny writes is so true. As you can see from the color samples on Amaco's site, a thin coat of a color doesn't look at all like a thinned out version of the color.  Often you get a dull brown or rust on your porcelain even if the color when applied in three thick coats is blue.

[Bill Kielb]

No doubt testing this combination is the only way to know the outcome. I am assuming that you are trying to accent the carving in some way without glazing it over solidly. To that end many use underglazes to highlight as well as over-glazes like China paint. Another common method is to use celadon to break in and around your carving. I included a variety of pictures below, some carved, some underglazed some celedon and underglaze with carving. All of the pics below are porcelain fired to rated cone with clear glaze or a celedon over the top.

Hopefully these will give you some additional ideas. All are possible and simply require experimentation.