Title: Patina on your piping.....
 Post by: CapnHarlock on February 24, 2007, 05:00:16 AM

Since it was mentioned in the Tactiles sticky post, I thought I would post a recent experiment that I feel has worked fairly well (imho) . (http://www.capnharlock.com/game/gallery/brass.jpg) is a photo of a PVC pipe-fitting painted to resemble somewhat-aged brass.

Base coat is sprayed-on Krylon Fusion (for plastics) hammered-finish copper (a US product- I'm not sure of availability, but it bonds to plastics without priming.)
When dry, a light dusting coat of metallic gold was unevenly-sprayed-on.

a wash was prepared, equal parts of Metallic Green, Metallic Sapphire Blue and Flat White acrylic hobby paints, heavily-thinned with water. The wash was randomly daubed on with a wide artist's brush and the part was allowed to dry standing on end to allow running and puddling. When dry it was sprayed with a satin-finish clear acrylic to seal.

The photo-flash added a bit of extra shininess, but it seems to be a fairly-good approximation of patinaed brass for plastics. This technique will probably be used for prop-production for a Steampunk-based LARP game in the near future.

Enjoy :)

Title: Re: Patina on your piping.....
 Post by: Hex on February 24, 2007, 05:10:27 AM

Very useful, thanks for sharing.
I may have to steal borrow this technique. ;)

Title: Re: Patina on your piping.....
 Post by: Honky-Tonk Dragon on February 24, 2007, 06:11:31 AM

Interesting approach.
I too may borrow some of this technique for my current project, a steampunk themed paint job on my Vespa.
Thank you, good Captain.

Title: Re: Patina on your piping.....
 Post by: sidecar_jon on February 24, 2007, 03:38:50 PM

very nice looks right too... may i pass on a tip too, to make real brass/copper go green. Put the object in a bag with some ammonia, it goes green like a good'un. Only problem is that it also attacks stressed areas and can bite through thin pipe. (i once made a brass rod "globe" to go round a fake mermaid, when i patinated it all the carefully soldered joints pinged apart!)

Title: Re: Patina on your piping.....
 Post by: Vermilion on February 24, 2007, 05:47:53 PM

This is great info! Thank you. With some foe rivits and the right meterial one could make some real neat pipe furnature. I think I just my have two for my next project ^.^

SIdecar-jon: do you just spray liquid ammonia onto the sides of the bag? How long would you leave in say an adverage thickness copper pipe?

Title: Re: Patina on your piping.....
 Post by: Tinkergirl on February 24, 2007, 06:05:13 PM

CapnHarlock - that's marvelous! I'm only sorry that Krylon doesn't seem to be available in the UK - I've seen it mentioned before. I have recently found a metallic spray paint that doesn't instantly melt PVC piping, however it does scrape off. I take it that Krylon doesn't scrape off?

Title: Re: Patina on your piping.....
 Post by: sidecar_jon on February 24, 2007, 06:48:59 PM

Id use liquid ammonia cleaning solution, put it on a saucer, place that in the bottom of the plastic bag, suspend the copper over it and seal the bag, you want the fumes acting on the copper not the liquid. i left mine for an hour and more if it looked like it needed it.

Title: Re: Patina on your piping.....
 Post by: CapnHarlock on February 24, 2007, 07:31:49 PM

Thank you :)

According to Krylon's advertising info, the "fusion" line of paint forms a molecular bond to the plastic surface, and (minor)
experimentation it doesn't crack and scratch off the way "normal" enamel/acrylic/latex spray paint does. It really does seem to be a different formulation, because (by direct observation) it doesn't adhere at all when the ambient air temperature is below about 40 degrees Fahrenheit - more like a lumpy-gel than a a smooth spray-coating (my back porch was too cold for working anyway..)

Apparently the HAZMAT import tax has made it too expensive to import into the UK on a widespread basis :( A bit of searching via Difference Engine Telegraphy has revealed one importer at (http://www.caswelleurope.co.uk/krylon_fusion.htm) but it seems outrageously-expensive.

Another search provided a hint that an airbrush (liquid) paint called "Special T" in the UK may have similar properties. (??)
(Note: I am in no way associated with the manufacturers or vendors of any of these products)

A fallback that works almost-adequately is to clean the PVC surface with acetone (removes the black US pipe-schedule printed info), sand the surface lightly with a fine emery-cloth then prime with a water-based latex spray paint and let it cure for at least a day (even though the can directions say 15 minutes), then spray on the metallics/add washes and seal with a clear coat.

You end up with a thicker coating that can obscure fine details, but at least it seems not to flake off when looked-at, much less actually used.

Perhaps I should acquire an armored-airship and begin a pirate-career, smuggling contraband artist's-supplies into Britain. :)

Title: Re: Patina on your piping.....
 Post by: Honky-Tonk Dragon on February 24, 2007, 07:36:28 PM

Another idea is to use paint with actual metallic particles in it.
There is this stuff (http://"http://www.prismaticpainting.com/items.lasso?type=Paint"). It is actually a two-part system, the first part is basically just acrylic polymer with different metal dust (pigment) dispersed in it, and the second part is an oxidiser. It'll cost you a little over $20 US for both parts, $30 if you opt for their sealer.
OR...
You could make it yourself. Golden Artist Colors sells just the acrylic polymer, I'd recommend GAC 100, to which you could add your own metal dust/fine shavings (if say, you've got them laying around lab...) after that layer dries, give a rub down with some fine grit sandpaper and use SIdecar-jon's oxidation technique.

On PVC, you would, of course, need to follow CapnHarlock's prep suggestions.

I haven't tried it, but it should work... I mean it's not Zepplin-science is it?

Title: Re: Patina on your piping.....
 Post by: Platyhelminthes on February 25, 2007, 07:13:56 AM

Honky-Tonk Dragon-- I've added my own copper powder to acrylic medium for oxidation effects on paintings before, and it works great! The method I used was to paint a layer of clear medium, then quickly dust the surface with copper while the medium was still wet. Once it dried, I filled a squirt bottle with vinegar and sprayed the embedded copper. After the vinegar evaporated, I had a lovely mottled verdigris effect, which I then sealed in with clear polycrylic spray.
Just a note, verdigris is an unstable pigment, and so the color did shift some over time.

Title: Re: Patina on your piping.....
 Post by: Cryptovitas on February 25, 2007, 07:45:38 AM

Definitely going to give this a try on my laptop. If it works well, you're my new favourite person.

Title: Re: Patina on your piping.....
 Post by: Fantômas on February 25, 2007, 08:03:14 AM

Not sure if anyone here is familiar with it...however Hobby Masters sells a variety of three products manufactured by A-West called Patina-it, Weather-it and Blacken-it.(http://www.hobbymasters.com/browseproducts/A-West-Patina-It.html)
quite effective correctly used, though also rather poisonous I fear. I used them on a project in 1999 when I was constructing my own fountain pen from scratch and was pleased with the results.

Title: Re: Patina on your piping.....
 Post by: Honky-Tonk Dragon on February 25, 2007, 08:35:43 AM

Hmmm....
You just reminded me that the inventory of my studio includes a jar of bronzing powder...
I may be experimenting with this sooner, rather than later...