Dark coloured acrylic paint showing through light coloured

[Martin]

I'm a novice painter. I'm using acrylic paint. I've heard that acrylic
dries quickly so you are able to overpaint quite quickly. My problem
is that if I overpaint a dark colour with a lighter one the original
colour darkens the second coat. If for example I paint red on black
the red is much darker than if I paint red on white even though I wait
for the paint to dry.

Is there any way of preventing this. All I can think of is painting
white on top of any dark colour before I then paint the desired colour
over the top of that.

Thanks far any advice.

[Paul Mesken]

Hi Martin,

Some paints are opaque, some are transparent and others
semi-transparent. Probably there's and indication of this on the tubes
(typically a square indicates transparency, a filled-in square is
opaque).

If you use a napthol red, for example, to overpaint something then the
original layer shows through because naphtol red is a transparent
color.

If you use a cadmium red (the real one, its ASTM number "PR108" should
be somewhere on the tube) then the original layer should not show
through because cadmium red is opaque. Of course, the paint should not
be applied thinly or diluted with water. Beware of imitations, the
cadmium colors are amongst the most expensive and are often imitated
by cheap organic colors. The problem is that organic colors are
typically transparent and the cadmiums are typically opaque (apart
from pale yellow ones).

You can also overpaint with Titanium White which is also opaque. Of
course, it should be done in a relatively thick layer and not be
diluted too much with water.

[King Rundzap]

Paul is right, and in general, whether a paint is typically
transparent or not, the thicker your new layers, the less the
underlying layers will show through. Both acrylic and oil are very
flexible, and you can easily make any color transparent (it just has
to be dilute enough--either use very little paint and/or dilute it
with a lot of medium--water in the case of acrylic), and with enough
effort, make any color opaque (use thicker paint, less or no medium).
With practice, you'll be able to control the effect you're talking
about and be able to use transparency or opacity to achieve just what
you'd like to see.

--King Rundzap

Paul Mesken <usu...@euronet.nl> wrote in message news:<m05mj0p0ch984n21t...@4ax.com>...

[sarpedon]

dar...@blueyonder.co.uk (Martin) wrote in message news

the advice by the others in this thread is correct. but you must
ignore people who say that acrylics are easy to use and dry in a
flash. one coat takes some time to dry depending on various factors,
like dilution with water or medium and ambient humidity, etc..
If you overpaint too soon you risk lifting up layers of the previous
coat, called tack. This ruins everything.
Whenever i have a major compositional change to make or otherwise
must repaint an area, the entire area must be repainted in white, not
once but at least two times, to return it to a pristine state. It
takes a long time, at least days, and some planning.
Adding white to any pigment will increase its opacity although it
dilutes and alters the color.

sarpedon

[Martin]

Thanks everyone for your help. I didn't realise some paints are sold
more transparent than others and I certainly didn't appreciate how
long acrylic takes to dry, I was overpainting within minutes because
it felt dry to the touch.