Bozothenutter Posted February 20, 2023 Share Posted February 20, 2023 Have used several modelling brands, even stuff that gunsmiths use. Lightly sand, cleaned with acetone, or brake cleaner, or alcohol. But nothing sticks....a sooty layer forms, that can be removed by looking at it angrily....with still shiny brass underneath 😡 Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 20, 2023 Share Posted February 20, 2023 There are a number of different metal blackening, browning, and darkening finishes. They are usually formulated for use with specific metal types, that is something for ferrous metals and others for copper/brass/bronze and others for pewter or tin based metals. That some chemical products work on metals outside their target is just luck. I don't know what the various modelling brand blackening solutions are. I can not find their safety data sheets and their descriptions are often not always very specific. Something that a gunsmith might use on steel or iron might work to some degree on brass photo etch or cast die metal tracks but perhaps not as well. Jax makes a number of products targeted at the jewellers market https://jaxchemical.com/ you will note in their descriptions the target metal they are designed for. If you are using these on photo etch then one specially designed copper/brass/bronze might be a better choice. You can find these products at any decent jewellery supplier. One of the traditional chemical finishes that jewellers used was done using liver of sulphur. You can still get this product ( Amazon, eBay, jewellers supply, etc ). It is very effective but also very smelly. Smells like rotten eggs. And speaking of rotten eggs, you can take a hard boiled egg and place in a small sealed container with your cleaned photoetch and leave it for few days. You might be surprised that it may produce a nice suitable patina on your photoetch. Some photoetch is not brass or copper based and may even be a stainless steel. Not many of these coloring products will produce any useable change in that case. cheers, Graham 1 Link to comment Share on other sites More sharing options...
Kingsman Posted February 20, 2023 Share Posted February 20, 2023 As noted, there are separate products sold for white metal and brass. I have some success with blackening etched brass but almost no success with blackening brass gun barrels regardless of preparation. White metal blackening works but the preparations lose their effectiveness over time, lose their blue tint and gunk up with a rust-like sludge. I'm no chemist but I don't see how the actual colour of the metal can be changed anyway. The chemical reaction must produce a surface deposit or coating. Blackened tracks also seem to develop a surface coating which comes off relatively easily. TBH I'm not sure I get the idea of blackening anyway. Brass parts are far better painted with a metal primer. Chemical blackening really does nothing for them and indeed the surface coating formed may work against paint adhesion. And tracks are simply not black, although the blackening agents rarely produce a true black - more often a browny grey. But this is not really an appropriate colour anyway. Track colour has been discussed on this forum many times. Most tracks of most nations since the late 30's have been a manganese-steel alloy. The natural colour of this fresh from the mould is a goldy-brown metallic. The initial oxide is a milk chocolate colour and the long-term oxide is a dark chocolate colour. The blackening agents perhaps take you in this direction: old tracks, years old. White metal track manufacturers continue to use a silvery alloy and 3D printed manufacturers are largely wedded to grey or rusty brown. I have contacted several manufacturers of both about pigmenting a more appropriate base colour but all said it is not possible. But that leaves us having to paint our supposedly-workable white metal and 3D links - which is hard work to get into all of the nooks, crannies and edges between the links and inevitably gums them up. 1 Link to comment Share on other sites More sharing options...
Jo NZ Posted February 20, 2023 Share Posted February 20, 2023 2 hours ago, ColonelKrypton said: One of the traditional chemical finishes that jewellers used was done using liver of sulphur. You can still get this product ( Amazon, eBay, jewellers supply, etc ). It is very effective but also very smelly. Smells like rotten eggs. It's even easier to get than that. Try your local garden shop - it's called lime sulphur. From memory, dilute 50/50 with warm water and put the warmed metal in it. The hotter it is the better it sticks. (I've only used it on silver, btw) 1 Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 21, 2023 Author Share Posted February 21, 2023 I'm trying to get barrels to look like, well blued steel barrels. Hence the tryout of gunsmith stuff. (Birchwood-Casey, got them for steel and brass) Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 21, 2023 Share Posted February 21, 2023 these solutions for ferrous or brass/copper/bronze do not work well for aluminum. There are products specifically for aluminum however. For example https://jaxchemical.com/shop/jax-aluminum-blackener/ but these produce a dull black finish different than a blued or parkerized like finish on a steel barrel. cheers Graham 1 Link to comment Share on other sites More sharing options...
Kingsman Posted February 22, 2023 Share Posted February 22, 2023 Paint has been invented........... Comes in many colours too. 😁 1 Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 22, 2023 Author Share Posted February 22, 2023 Been reading up on this.... Apparently pickling liquid is a big help....trying some vinegar next. Link to comment Share on other sites More sharing options...
Chief Cohiba Posted February 23, 2023 Share Posted February 23, 2023 This is a topic I'm interested in as well, as I'm currently in building the white metal kit of Model Factory Hiro's Knucklehead, which inlcudes a working chain made of photo etched brass. 15 hours ago, Kingsman said: Paint has been invented To answer Kingsman's remark; agreed in most of the cases, but in some rare fields paint is not the optimal solution. Two reasons; paint still is prone to abrasion and wear, which usually is of no relevance in a static model, but if there is some movement (as in this chain situation) it might be visible. Also, paint usually chips in larger chunks, so even on places usually showing some wear, it might look out scale. Connected here is, that you can't glue a painted surface, especially not with CA. Usually the bond between CA and the layer of colour is stronger than between colour and surface. Second reason is, that on very small parts several layers of paint add volume, so the shape may be distorted. Again; think if a chain in 1/9, with all these tiny pieces, or working on slotted screws in this scale, it starts to become an issue. So, I'm looking for a tanning/browning solution as well, I found one mentioned in a Video building a Hiro bike, but can't remember. Will do some investigation and if I find it, will post here. Of course will also check the solutions mentioned here. Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 23, 2023 Share Posted February 23, 2023 On 2/20/2023 at 5:48 PM, Kingsman said: I have some success with blackening etched brass but almost no success with blackening brass gun barrels regardless of preparation. That is an interesting observation. There are many different alloys of brass - yellow brass, red brass, naval brass, leaded brass, etc. Brass is an alloy of primarily copper and zinc but may contain traces of tin and lead. Bronze is an alloy of primarily copper and tin. Variations in the percentage of the different alloying metals is what produces the different alloys. For example, red brass contains a higher percentage of copper giving it a more reddish appearance, naval brass contains a higher percentage of zinc and only a trace amount tin giving it's high strength and corrosion resistance, and leaded brass contains a larger percentage of lead making it more suitable for machining in the manufacturer of turned products such as screws and similar fittings. I suspect that the difference in type of brass used for photo etch versus a turned brass barrel is what has led to @Kingsman 's observation. I had never considered that before but then I had never tried to blacken a brass gun barrel before. I have some different types of brass in the workshop, perhaps I will have to try a simple experiment to see for myself. On 2/20/2023 at 5:48 PM, Kingsman said: I'm no chemist but I don't see how the actual colour of the metal can be changed anyway. The chemical reaction must produce a surface deposit or coating. I am no chemist either but I have worked with metal and a number of these over the years. These chemical products don't actual change the colour of the metal. Rather they produce a chemical induced oxidation of the metals surface. On copper and bronze this is often referred to as patina and produces a greenish finish and would happen naturally if left long enough. On ferrous metals, gun bluing chemical turns red iron oxide that naturally forms on the steels surface into black-blue iron oxide giving the metal a dark bluish finish. In addition, heat and flame can be used to promote colour changes through oxidation. One technique used by watch and clock makers is to carefully heat a steel screw until it turns a very attractive blue colour. For an example this video on youtube demonstrates: https://www.youtube.com/watch?v=1N45kwD6S8g https://www.youtube.com/watch?v=lqfIwjUNIJM They are short videos and the heat bluing is shown towards the end. cheers, Graham Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 24, 2023 Author Share Posted February 24, 2023 Psa: do not forget your PE in the blueing solution it turns to dust.... Second attempt went better though. 2 min in 50/50 cleaning vinegar Rinse 1 min in Birchwood casey 'brass black' 50/50 with demineralised water Rinse and let dry. Smooth looking finish, could be rubbed with a soft cloth, eventually shows darkish brass. Trying the 'blue' version for steel next. Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 24, 2023 Share Posted February 24, 2023 2 hours ago, Bozothenutter said: Second attempt went better though. 2 min in 50/50 cleaning vinegar Good idea. I noted your earlier comment on pickling liquid. Why dilute the cleaning vinegar 50/50 and not use it as is? Pickle is used by jewellers for cleaning oxides and flux off of soldered pieces. Also used by those building small working model steam engines and locomotives for basically the same reason - removing surface scale ( oxides ) and flux after soldering. There is a wide variety of pickle to choose from, a number of commercial products and numerous home made variations as well. Typically kept in something like an old crock pot in order to warm the pickle which makes it much more effective. You might find the cleaning vinegar more effective if placed in a bath of warm to hot water. In your use the cleaning vinegar is probably not only helping by cleaning the surface of the brass but also etching it slightly which would provide a bit tooth for the following bluing step. cheers, Graham Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 24, 2023 Author Share Posted February 24, 2023 2 hours ago, ColonelKrypton said: Good idea. I noted your earlier comment on pickling liquid. Why dilute the cleaning vinegar 50/50 and not use it as is? Pickle is used by jewellers for cleaning oxides and flux off of soldered pieces. Also used by those building small working model steam engines and locomotives for basically the same reason - removing surface scale ( oxides ) and flux after soldering. There is a wide variety of pickle to choose from, a number of commercial products and numerous home made variations as well. Typically kept in something like an old crock pot in order to warm the pickle which makes it much more effective. You might find the cleaning vinegar more effective if placed in a bath of warm to hot water. In your use the cleaning vinegar is probably not only helping by cleaning the surface of the brass but also etching it slightly which would provide a bit tooth for the following bluing step. cheers, Graham No real reason really, it was what was mentioned on one of the many pages I encountered in my search. Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 24, 2023 Share Posted February 24, 2023 1 hour ago, Bozothenutter said: No real reason really, Fair enough. After a bit of thought, it seems that treating photoetch to a wash/pickle/etch in strong vinegar may be benificial prior to painting or gluing in place. cheers, Graham Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 25, 2023 Author Share Posted February 25, 2023 After drying: After a light rub with an old T: 2 Link to comment Share on other sites More sharing options...
ColonelKrypton Posted February 25, 2023 Share Posted February 25, 2023 That does look quite nice. A well used and war weary cooling jacket for a Spandau. cheers, Graham Link to comment Share on other sites More sharing options...
Black Knight Posted February 25, 2023 Share Posted February 25, 2023 Has any one tried black stove & grate polish? 1 Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 25, 2023 Author Share Posted February 25, 2023 Actually making nickel acetate atm. Attepmting nickel plating and then blueing that.... 1 Link to comment Share on other sites More sharing options...
Bozothenutter Posted February 27, 2023 Author Share Posted February 27, 2023 Master are being really nice and sending me a new PE set. Link to comment Share on other sites More sharing options...
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