Painting Hydrocal FGR 95
Eldey
water based acrylic product with bronze powder as the pigment, to put a
bronze finish on sculpture made of Hydrocal FGR 95 fiberglass reinforced
gypsum cement. It calls for a clear base coat sealer, "Modern Options Primo
Primer and Clear Sealer", as the base coat. The problem I am having is that
with this product being water based, the gypsum sucks up the primer so fast
that it is impossible to get a really smooth coat without brush strokes and
overlaps. I don't have the facilities to try spraying it instead of
brushing. Does anyone have suggestions on how to get this stuff on more
smoothly, or suggest a product that works better but will still have the
durability and color of bronze that this acrylic product has?
Dan Spector
Flood Co. I get "stone white" and tint it and add brz powder from Pearl. And
I love my finishes. You can buff it when dry (very fast) and I never lose my
texture.
--
Dan
<arch...@earthlink.net>
http://www.archicast.com/Lifecast-page1.html
> From: "Eldey" <eldeystudio@"NOSPAM"mindspring.com>
> Organization: MindSpring Enterprises
> Newsgroups: alt.sculpture
> Date: Thu, 12 Jul 2001 13:40:07 -0500
> Subject: Painting Hydrocal FGR 95
Eldey
Who is the Flood company? Is my problem the fact that the sealer I am using
is as thin as water and soaks in instead of laying on the surface? Do I
need a primer before using acrylic paint on raw plaster so it won't flake
off later?
Eldey
"Dan Spector" <arch...@earthlink.net> wrote in message
news:B773CC18.863D%arch...@earthlink.net...
Michael Gainer
metal primer from a spray can. The Modern Options stuff appears
not to care too much what the substrate is.
In order to minimize brush marks, put on *really* thin layers in several
coats. Just before it gets really tacky, you can run your brush in several
directions to minimize the strokes. I found this too time consuming,
though, and recently got an airbrush. Since it's all one color, the brush
doesn't _need_ to be high quality.
--
Mike Gainer
http://www.bnglifecasting.com
Jeff Brown
> > a
> > water based acrylic product with bronze powder as the pigment, to put a
> > bronze finish on sculpture made of Hydrocal FGR 95 fiberglass
> > reinforced
> > gypsum cement. It calls for a clear base coat sealer, "Modern Options
> > Primo
> > Primer and Clear Sealer", as the base coat. The problem I am having is
> > that
> > with this product being water based, the gypsum sucks up the primer so
> > fast
> > that it is impossible to get a really smooth coat without brush strokes
> > and
> > overlaps. I don't have the facilities to try spraying it instead of
> > brushing. Does anyone have suggestions on how to get this stuff on
> > more
> > smoothly, or suggest a product that works better but will still have
> > the
> > durability and color of bronze that this acrylic product has?
I just finished a couple dozen pieces using this stuff... and learned a
lot in the process. My pieces were cast with #1 casting plaster, which
is supposedly designed to reduce absorbtion, but I don't notice a huge
difference between that and the absorbtion of hydrocal.
I tried several different kinds of brushes and even spent about $200
bucks for an airbrush and compressor in the search for a good way to
finish these puppies without the process taking forever. To make a long
stort short, in the end, I found that plain ole 1" foam brushes (ten
cents each!!) worked best. But it's not quite that simple either...
To begin with you don't even really need the sealer, depending on the
sort of finish you are trying to achieve, but I prefer to use it because
it allows the final finish to have a glossy/shiny appearance, like that
of a well worn piece of bronze. I suggest just applying thin coats of
sealer until the surface is glossy. (since the sealer is milky white
when wet, and your plaster is white, be sure to work under good lighting
so you can see what you are doing.)
The thing that helped me the most was when I realized that not all foam
brushes are created equal. Some are more coarse and some are more fine.
Here in Texas, the ones with the red plastic handles seem to be coarse,
while the fine ones have wooden handles. There are also coarse ones with
wooden handles... Hard to describe, but the difference will be obvious
when you put them side-by-side. BTW, I found some of the fine ones at
Michaels recently. In my experience the coarser type has a slightly
darker color.
Anyway, the point is that I was having to apply 4 or 5 thin coats of
bronze to get good coverage without gunking up the fine detail of the
pieces. By switching from the coarse to the fine foam brushes I was able
to get that down to 3 coats. (that may not sound like a big deal, but it
is if you multiply by 30 or so)
Before I made this discovery, I wasted many hours and dollars teaching
myself why spraying the bronze paint is a bad idea (at least for me).
The idea of spraying one nice smooth coat was so tempting compared to
having to apply 5 coats by hand... But the problem with an airbrush is
that it prefers water-thin paint. So thin, that if you thin the bronze
paint (with acrylic thinner) to the point where it sprays well, the
metal particles will simply fall out of suspension. Even if you do get
it to work somewhat, the surface will never have the metal-y finish you
want. Instead the action of the tiny droplets of paint passing through
the air causes them to dry slightly and you are likely to end up with a
rough-ish, dry-ish bead-blasted type finish. Spraying also seems to give
the surface a permanent milky-white tint. Maybe if you had a
mini-airless sprayer... you could do better. But the problem with
airbrushing is that you just can't thin the metal containing paints down
like other kinds of paint.
> I have used Modern Options over TufStone, and I typically use a
> metal primer from a spray can. The Modern Options stuff appears
> not to care too much what the substrate is.
Sounds like a good idea to me. Especially if you wanted to have a
slightly lighter undercoat for a rubbed-through patina effect.
> In order to minimize brush marks, put on *really* thin layers in several
> coats. Just before it gets really tacky, you can run your brush in
> several
> directions to minimize the strokes. I found this too time consuming,
> though, and recently got an airbrush. Since it's all one color, the
> brush
> doesn't _need_ to be high quality.
Well, I would apperciate any helpful hints on how you make this work!
Jeff
Dan Spector
brushmarks. Ask a Sherwin-Williams dealer to get it. I'll put on multiple
coats of bronze just because I want different tones in it.
Hydrocal is very dense plaster, while #1 Casting has a starch that moves to
the surface to lower absorbtion. You must compare it to Molding Plaster to
see what an improvement it is.
> From: Jeff Brown <jwb...@jump.net>
> Organization: Jump.Net, Inc.
> Newsgroups: alt.sculpture
> Date: Mon, 16 Jul 2001 11:37:26 -0500
> Subject: Re: Painting Hydrocal FGR 95
Michael Gainer
> > though, and recently got an airbrush. Since it's all one color, the
> > brush
> > doesn't _need_ to be high quality.
>
> Well, I would apperciate any helpful hints on how you make this work!
Unfortunately, I didn't find it too tough, so I don't have much
in the way of what-not-to-do to share. I just mixed the Modern
Options 1:1 with Golden Paints' airbrush medium. That's still
thick enough not to have all the metal fall out of suspension.
20 or 30 PSI through an Iwata Eclipse, and it comes out fine.
Things that were less good:
- With the addition of the airbrush medium, it needs at least 12
hours to dry so that it isn't tacky. Too much retarder? I may
try again with 2 paint, 1 airbrush medium, and 1 water.
- The paint goes on wet, not dry. This is a Good Thing if you
want a smooth finish, but less good if you had different expectations
from airbrushing in general. Fortunately, I'm a complete novice.