Cast Bronze Look

[Gregg Vaughn]

I have a customer looking wanting a picture (head and shoulders) to have the look of cast bronze. They had used cast bronze in the past, but it has become too expensive for them. Does anyone know of a material that will produce the look they are looking for?

The picture will be on a large plaque.

[Mike Null]

You can call Pella Engraving and see what they might be able to do in zinc.

[Wil Lambert]

I have a customer looking wanting a picture (head and shoulders) to have the look of cast bronze. They had used cast bronze in the past, but it has become too expensive for them. Does anyone know of a material that will produce the look they are looking for?

The picture will be on a large plaque.

I do this for relief type sculpture pieces. I use a cold cast resin to archive the look. I have included a picture of the last piece I just did.

Wil

[Mike Null]

Will

Very impressive. Is that a trade secret or would you share your technique with us.

[Rodne Gold]

Cold casting is relatively easy , essentially you are mixing a bronze , copper , brass or aluminium powder with a casting resin.
Mostly the powder is expensive , so one doesnt cast a major piece with it entirely , the accepted practice is to brush coat the mould with a thin skin of "cold cast" and then to use a much cheaper filler for the bulk of the casting.
The effects of the resin/metal mix depend on your proportions of metal used , but we found 60-70% to be a good ratio. The higher the ratio , the more "metal" the item looks.
The metal powder needs to be "exposed" after casting , ie you need to buff , polish , sand or patina the item to bring out the full metallic look.
You can generally drill , mill , engrave and route the cast object too. Laser engraving is also an option.
If you want the piece to be the weight of cast metal , the cheapest way to backfill the cold cast skin is to use plaster of paris and either lead or iron shot.
Our first effort was a wrestling belt front plate , which after our first disaster , came out fantastically. The disaster was that we dumped in all the metal powder at one time into the casting resin and it went exothermic and fizzed and bubbled and solidified all over the place.
The castings will show amazing detail , and if you have a bit of savvy , you can make masters and moulds with your lasers and routers/cnc engravers.

The process is to make a master which is a replica of the item you wish to cast , use Room Temperature Vulcanising mould rubber (called RTV) to make a mould and then use the mould for the casting.
There are fairly cheap rtv's around , but using them with some resins will result in mould tearing and agressive attack of the rubber (assuming you doing many items)
A good RTV will result in a mould you can even pour low melting point metals like zinc , lead , pewter etc in .
We also add a colourant to the resins , like brown for bronze , yellow for brass , red for copper and white for ally.
Rub n buff works very well on these castings too , for added acccent or patination.
When making masters , remember that thin rubber bits will tear or deform , so for example , you must leave space between letters otherwise you will get poor castings.
You also get about 3-5% shrinkage between master and casting , sometimes more , so take that into account.
If you are sculpting , we have found that jewelers wax is very good for delicate pieces and carves wonderfully and can be really nicely smoothed. Cant be lasered tho.
If you have a laser , its realtively easy to make a 2d photo master by using photograv and a thickish substrate , burn deep.
Making bass relief masters on a laser is a pain in the ass ..... you have to remove most of the background and leave letters standing and cannot EVER get a decent smooth background. We have overcome this by using formica or perspex as a background and vector engraving the outlines of the elements and then laser cutting the elements and gluing them on , then do a border.
The laser will always give lousy results if you engrave away large areas. You can ameliorate this by doing a polishing pass , like going over a plate with a 100% speed , 50% power type pass to "polish" the ridges , still not ideal.

[Wil Lambert]

No trade secret.I will share some information on it. It can be researched more online if needed. I use this process as an alternative to actual casting. Costly for indoor use. It will last outdoor but not like actual bronze.

The process is called cold casting. It is a method of using a resin that is filled with up to 50% metal powder. The steps that take to do this included making a model, making a mold from the model, casting the piece, and finishing the casting.

Making a model can be done in anyway you know how. ~ clay, wood, metal foam, ect. Take you choice on this. I use ArtCAM to sculpt the faces out. All of the sculpting is done by hand in ArtCAM not a wizard. After the model is complete in ArtCAM I use a cnc to cut the model out of Sign Foam or walnut. Depends on what I have lying around. Foam if teeter but walnut doe well too.
After the model is cut you must finish the model by sanding and painting. Always remember every and I mean every detail that is on the model will turn out in the mold. Silicone picks up some of the finest details including the grain and pours of wood or foam.

After the model is complete you need to make a rubber mold from it. I use silicone for my mold material but they make many mold materials for this process.

Once your mold is cured you need to start mixing the resin for the final piece. You will include about 33% fine metal powder in the resin. The metal powder is a special grind that is made for this. It's about $26 a pound. After the resin is mixed you will go about casting the mold like any other casting. I suggest you practice casting with regular resin before using the metal filled. It can get costly to practice with metal in it.

Once the casting has cured (about 1 hour) you can strip the mold form your casting. At this point you will burnish the piece with steel wool to give it highlights and a shine. If you desire the casting can have a patina applied to it. Once all the finishing is done you need to clear coat the piece to prevent tarnishing.

There are some trick you will learn over time. Hope this helps a little.

Wil

[Joe Pelonio]

Is the powder the same as what I use in clear for fake metal on the surface of laser cut lettering, the stuff by Cres-Lite? I think it was $35/quart.

[Stephen Beckham]

Gregg - have you looked at Ikon Metal? I've looked at it, but it's expensive and therefore - I'm not willing to experiment with $$...

Anyone work with it before?

Signware house has info on it - I'm not sure where else it's available...

http://www.signwarehouse.com/engraving-supplies-IKON-p-ENA-IK-612-B.html

Steve

[Joe Pelonio]

I looked into that and it's basically the same as what Rodne and Wil are doing, cast resin with metal powder in it. I too am unwilling to spend the $ to test it until I have a customer asking for something like it. Seems like $19+ is a lot for a 6"x8" piece.

Here's the data sheet on it, it's a pdf but I had to zip it to fit.

[Wil Lambert]

Is the powder the same as what I use in clear for fake metal on the surface of laser cut lettering, the stuff by Cres-Lite? I think it was $35/quart.

Joe,

I don;t know if it is the same material as you use. I buy the powder from Smooth-on. Same company I get my resins and silicone from.

[Gregg Vaughn]

Thanks for all the input ... I'm not sure I've found exactly what I'm looking for, but once again I have learned much from the collective knowledge that everyone has shared.

[Richard Rumancik]

The cold cast bronze is very attractive, but as you can see you have to expect to invest a lot of time and money into it. Also if you want a 3D image you need to be an artist like Will (I know he is using ArtCam but don't think for a minute that the image he has popped out automatically from the software.) ArtCam is not inexpensive either and has its own learning curve. Also be aware that the cold cast resins, polyurethanes, silicones, have a shelf life especially once opened. Cold casting is probably not the best for casual use or you will waste a lot of material.

Ikon metal is inexpensive compared to cold casting resins but of course they are for two different things.

I did see at a trade show a pseudo-bronze plaque in acrylic. It was painted with some type of bronze paint. It had been laser engraved with the 3D function. If the customer can accept a 2D image in metal (more like a Photograv image than relief) it would be a lot easier. If you go 3D, you have to figure out who can make an appropriate greyscale 3D image for you as there is probably no easy way in Corel to do it. There are some companies that offer this service.

If you want to do most of this project yourself stay with 2D. It could still be raised letters and raised image. You can texture the backgound to look like cast metal using textured fills. (You have to first laser the pockets deep with a solid fill and then follow with a pattern fill). You don't want to see the raster lines in the background. I have experimented with a "cement" fill (as in concrete) and it works quite well for a background. I don't try to make the background smooth. You might be able to achieve a pebbled look with appropriate fill.

You could do some highlights with Rub-n-buff or a second color of bronze so it isn't all the same color.

If you get a few brochures from the large metal plaque suppliers in the industry you will see that they do both 2D and 3D images. It will give you some ideas of what look to aim for.

[Craig Hogarth]

I looked into that and it's basically the same as what Rodne and Wil are doing, cast resin with metal powder in it. I too am unwilling to spend the $ to test it until I have a customer asking for something like it. Seems like $19+ is a lot for a 6"x8" piece.

Here's the data sheet on it, it's a pdf but I had to zip it to fit.

If you call them, they'll give you free samples to work with.

[Levi Chanowitz]

This may be exactly what I am looking for. I am looking for a lower cost alternative to bronze Plaques I want to supply 3" x 7" bronze looking plaques, each one with different text. I would do over 100 per month (hopefully) and I could get at least $38 each There would be around 4-5 lines of text. Do you think this would work?

Would it match the bronze?

Would it look fake?

I have a laser engraver and a few mechanical engravers. How would you suggest I make the moulds

[Richard Rumancik]

Levi - do you mean that cold casting may be what you are looking for? I was a bit confused as your message was attached to a another message pertaining to the IKON product.

But since you say "how would you suggest I make the molds" I assume you mean molds for cold casting.

In my opinion you may find that this is not profitable enough on a $38 item to be viable. You first need to make a master (presumably by laser or CNC router), make a silicone rubber or polyurethane mold off of it, and then cast the item. There are a lot of steps involved in doing this. For high-end work (where you could charge say $250 for cold casting vs. $500 that a real bronze casting would cost) cold casting may be quite viable. But I think you will find that there is a lot of labor, materials cost, as well as risk of the casting not turning out right.

However, it might be worthwhile to get some literature on the subject. I suggest Smooth-On (www.smooth-on.com (http://www.smooth-on.com)), Goldenwest Manufacturing (search FastCast) and Synair www.liquidplasticsolutions.com/synairproducts.htm (http://www.liquidplasticsolutions.com/synairproducts.htm)

Synair has some excellent videos which may be helpful to anyone interested in this. But keep in mind that the laser/engraving component tends to be fairly minor relative to the moldmaking, casting and finishing steps.

[Scott Shepherd]

http://www.sawmillcreek.org/showthread.php?t=59665&highlight=IKON

Craig took some videos of him cutting it. Worth a look.