adding bronze patina to a plaster sculpture

[Daveum79]

Hi everyone,

Sorry if this was supposed to go into the painting section, I wasn'tsure as where this was was more appropriate.

I work with plaster in particular Crytacal R and having been making lots of test pieces with the intention of maybe selling some when I can find the best way of painting & finishing them. One issue I've found is when applying acrylic paint either straight onto plaster or with an undercoat of primer, the plaster still scratches very easily. I want to use metallic patina wax such as bronze over acrylic matt black paint so as to try and get an aged finish. I've thought of adding gesso over the plaster, although havn't tried this as of yet as this might make the paint adhere a little more and less scratch resistant although I can'tbe sure without trying. My question is, if I were to apply a metallic petina what is the step by step process.

Do I start with gesso over plaster then primer then acrylic, with the patina wax then a matt varnish finish, or is the primer not required.

Or should the matt varnish be applied second to last and then the patina last?

Is there anywhere in the UK to get a good patina aged bronze effect wax?

 

[valiant]

Ideally, the plaster surface needs to be sealed with something, as it remains very porous. I have mentioned before that, when I worked in the ceramics industry, we sealed the plaster with an epoxy resin liquid, brushed on. This needs to cure. Once cured, the plaster surface becomes very hard and will take auto paints, etc. A substitute method would be to seal the surface with a polyurethane varnish or PVA. Neither of these, though, will prevent scratching, as they are not as hard as the resin. I think you need to concentrate on making the surface as hard as possible, prior to adding any paint effect, otherwise, all finishes will inevitably scratch...

 

[Daveum79]

Thanks for the reply. Would gesso not be suitable as I've tested the gesso out but not on plaster just yet and the gesso dries very hard. I thought about possibly painting over sculpture once dried with gesso then adding acrylic directly over the gesso. To be honest I can't work with epoxy resin. I've tried it but the few I've tests made take very long to completely dry and and this time on top of the time it takes for the plaster to dry out just isn't worth it when I have a relatively quick turnaround time once the plaster has dried out. If I were to use a thick pva glue would this not soften say in sunlight?

Let's say I were not to paint the sculpture as intended and left it the same colour when dried out which is white. Is there any kind of patina that has an old rustic appearance to apply over the top? That way it wouldn't matter if the sculpture took the odd scratch in places as it would just add to the overall character. Obviously bronze or any other metallic patina wouldn't work over white but do they sell anything that gives an aged brown or dirty colouring to the white that I could try. Alternatively, if not a patina something else?

 

[valiant]

Ive never used gesso, so cant comment, sorry. How about adding colour to the Crystacal, like powder paint, or some other body stain, as it is being blended...? Then if it scratches, it wouldnt show,as much..? The PVA should be thinned, to the consistency of milk, before sealing the surface. I wouldnt advocate painting neat PVA on...