[Clayart] Hot wax

Robert Harris robertgharris at gmail.com
Mon Jul 15 08:20:02 EDT 2019


Some of the copper reds I use are pretty thick.
I have noted a couple of things about wax emulsion.

1. The thicker the layer the harder to dry fully and properly. Any water
based coating is going to have this problem. Since moving to hot and dry
Colorado things have improved significantly. If you live in humid Florida
(as I did), you are always going to have problems.!

2. Both thin and thick layers can form rougher surfaces (either because of
brushing issues with thick emulsion, or roughness of the bisque with thin
layers). This automatically prevents good repulsion of the glaze.

Hot wax works by cooling rather than evaporation so is always going to
"cure" better, and faster. Generally it also has a smoother surface which
helps repel the glaze better. The downside is that it cools very fast and
is hard to handle. Frankly I've also seen hot wax have problems repelling
the glaze if it's not applied smoothly.

There are three routes of investigation that occur to me.

1. Find some sort of coating that does not rely on evaporation. Either a
very thin two part epoxy or a coating that relies on oxidation (some of the
polyurethanes work this way). This probably doesn't much fix your speed
issue. You also want something that is high enough gloss to really repel
water.

2. A coating that uses more volatile compounds to dry. Shellac is an
example although as LT notes, this apparently is susceptible to water
damage and therefore doesn't repel water very well. Some of the modern
lacquers can be diluted with acetone and dry very fast and are more water
repellent. Acetone etc has a very very low surface tension and I could see
it not keeping a tight enough line.

3. If we focus on the water repelling properties, there are some very high
tech water repelling silicones that might do a better job than even hot
wax. Obviously silicone caulks spring to mind but probably aren't suitable
for your application (mostly because of viscosity). But there are also
silicone concrete sealers and fabric sealers than might work really well
(I'm pretty sure I've seen very tight water beads on coated wood and
concrete). These tend to have longer drying times, but you might find
something that really repels the glaze.

I use 100ml syringes for measuring specific gravities and the glaze will
degrade the plastic and rubber plunger so it's almost impossible to move.
However a single coat of silicone leather protectant completely renews it
and I've noticed the glaze, however thick, really beads up nicely.

Robert



On Mon, Jul 15, 2019, 4:51 AM Paul Gerhold <gerholdclay at gmail.com> wrote:

> My problem is the glaze is clay based and has to be very thick to do what
> I want to achieve. Thin resists just coat over after a couple of coats of
> glaze.  Can actually clan with moist Q tips but way to much work to be a
> viable technique. Need a way to get a thick resist layer that dries at a
> reasonable rate.
>
> Paul
>
> > On Jul 14, 2019, at 4:15 PM, Robert Harris <robertgharris at gmail.com>
> wrote:
> >
> > Paul -
> >
> > I don't see why that wouldn't work. I'd imagine you could use light oil
> or
> > white spirit to reduce the melting point to work well with any
> temperature
> > setting/fluidity wanted.
> >
> > I'd also mention that I always dilute my wax emulsion quite
> significantly.
> > This aids drying time, but I have to admit I still like to give it an
> hour
> > or two, which really helps even thick glaze come right off.
> >
> > As an off beat idea how about using lacquer or something similar that is
> > alcohol based. Should dry much faster. I know people who do water etching
> > on leather hard clay like lacquer. No idea if it work on bisque however
> (I
> > could imagine the layer not being quite thick enough to get into pores
> etc).
> >
> > Robert
> >
> > Ribert
> >
> >> On Sun, Jul 14, 2019, 12:10 PM Paul Gerhold <gerholdclay at gmail.com>
> wrote:
> >>
> >> Has anyone tried using an electric tjanting tool to apply hot wax to
> >> bisque. I have tried several liquid wax resists and am so far unhappy
> with
> >> the drying rate.
> >> I will try lowering bisque but I need a thick wax line to work with my
> >> thickly applied glaze.
> >>
> >> Paul
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