Brass Blackening questions

[stevenmh]

The model I'm about to start has some brass photo-etched parts that need to be glued together which I want to color by blackening with Birchwood Casey.  My questions are:

1. if I glue them together first with CA will the blackening process eat away the glue?
2. if I blacken them first will gluing no longer work??
3. do I just worry too much???

[RichardG]

I only know part of the answer - the blackening will not work where there is CA glue. The part must be very clean. I use acetone to clean followed by a bath in a Sparex pickling solution.

[BANYAN]

Hi Steve,

 

I have found it is not so much the blackening solution, but the chemicals used for cleaning the assembled parts that will create problems.  I always solder my PE that has to be blackened, but it may be possible to glue them if you do not use acetone etc for cleaning.  Using a stiff bristle brush (scratch/fibre pencil) or brass/soft rotary brush etc may clean them enough depending on how delicate they are.  BUT the part has to be very clean and no finger oils etc for blackening to work properly.  As Richard points out, any excess glue must first be removed. 

 

If you try to blacken the individual parts first you might get away with it but you must get the blackening process right.  Too many instances of blackening I have seen left a residue/thin coating of black which will come away very easily if glued - very weak joint.  Using a slow blackening process by diluting (I use 50/50 or weaker) solution, then buffing the item such that you get a polished iron grey/charcoal grey finish that still appears metallic may work with CA.

 

cheers

 

Pat

[stevenmh]

Thanks to you both - will let you know if I succeed.  The Cairo model has photo-etched gun port lids that are glued to the photo-etched armor plates, so I can burnish the backside of the lids and that should not be visible.

[mtaylor]

Test first on some scrap brass if you have it. Possibly the thin CA may work using as little as possible.   As for blackening... they could always be painted flat black.

[barkeater]

I have blackened after gluing and there was loosening. I wont do it again.

Rich

[stevenmh]

Good to know, thanks.  Likely will stick to paint

[allanyed]

Steven,

Instead of glue, you might consider soldering the pieces together then filing away the excess solder, if there is any, back to bare metal which will allow the part to be blackened with no light spots.  If you must glue, epoxy may work better for you  as it easier to control and gives time to clean up excess before curing.

 

 Allan

[Laggard]

I’ve never been able to blacken brass.  Paint is the best I could do but that inevitably scrapes off. 

[Roger Pellett]

If you want to glue brass parts together instead of soldering JB weld epoxy sells a product for gluing metals together that dries dark grey.  It works well on brass and copper.  I sand the parts first to get rid of oxide and to the mating surfaces some “tooth”.  You can find it at any hardware store.

 

Roger

[Jonathan_219]

Just finished another attempt at getting consistent blackening on my cannons and found that using my Dremmel with a polishing pad on the cannon after cleaning greatly improved the result. I've only been cleaning with rubbing alcohol since my workspace is in the house and just don't want acetone or similar solvents in the house. My process was clean with alcohol and a rag, rub dry, polish with the Dremel pretty vigorously and then wipe clean one last time to remove any dust from the polishing process. I used a small container with about 50/50 Casey Brass Black and distilled water and tie a thread around the cannon and keep the cannon off the bottom of the container and move the cannon about fairly frequently. I do two at a time and it takes a couple minutes for the process. Before I started polishing the process took almost 10 minutes and the finish was splotchy.

 

The finished product still has a bit of a matte finish and a slightly powdery look but much less powder than before I started polishing. I finish the cannons out by rubbing a very small amount of clear candle wax over them with a rag, tried beeswax but the candle wax worked better. This gives the cannon a much more realistic finish and texture to my eyes.

 

I'm hoping in the future I can continue to get a fairly consistent result by polishing since personally I like the look of blackened over paint. These were my last cannons on this ship so it will be a while before I get to try this process again. I've been following this thread as I've tried to improve my process and wanted to share some positive results, it wasn't as easy as I thought when I started but once I got a process it went pretty quickly.

[Roger Pellett]

Testor’s  Dulcote!

 

I have been recently been painting cast metal model soldiers.  As painted with acrylic paints the surface is dead flat and the paint is easily rubbed off.  Dulcote is a matte spray lacquer.  A quick shot of Dulcote makes a remarkable difference.  I also spray it over blackened brass.  The finish is also much more durable.  I like Dulcote much better than the hardware store clear matte spray.  

 

Roger

[Dr PR]

Two comments if you solder the parts together.

 

1. I use a Dremel with a wire brush to remove any excess solder. The soft solder is removed easily, but the harder brass isn't cut into. This works very well - too well if you aren't careful, because the brush can remove the soft solder down into the joint! It leaves the surface very shiny. Buffing with polish/rouge can produce a mirror finish.

 

2. Solder doesn't just flow over the brass, it dissolves into it (and the brass dissolves into the solder). This is the basis for the strength of the joint. Even after you have brushed away excess solder there will be a solder "stain" on/in the brass, and that may effect the blackening process.