This page will interest those of you who have nicely laid trackwork and nicely detailed models but are fed up with those highly shiny and thus very noticeable overscale wheel flanges on N gauge wheels. The following processes are also of use to those of you using metal parts with detail that you don't want to hide under a coat of paint. This process can be applied in all modelling scales and `full size' engineering projects.

Cold Blueing is a process used to make steel components of guns and other metal hardware Black on the surface, this is achieved by covering the surface of the metal with a Selenium Dioxide solution either in liquid form or as a paste, and allowing the potent chemical to attack the surface of the steel, which quickly turns the surface of the steel from grey/silver to a dark blue/black. There is also a form of this bluing process that uses heating to optimise the effect, known as `Hot Blueing' but Cold Blueing is safer, less fuss and all that is required for the small scale wheels & parts used in N gauge and most small modelling scales. This process will of course work for any scale of model and is actually used in maufacturing to give firearms, tools and other metal equipment a nice black finish. I have touched up the scratches on a pair of Xuron cutting shears, allen keys, and other tools with it which now look almost new again!

USE: It is always of utmost importance to handle any potentially hazardous chemicals with care. Selenium Dioxide is a poisonous substance and requires careful handling, read all the manufacturers instructions and recommendations on use of their product before use. DO NOT use Selenium Dioxide in the kitchen! or near any surfaces used for food preparation. I would also recommend the use of a good quality `barrier cream' to protect your skin from contamination and industrial strength `Poly Bead' hand cleanser such as `Tufanega'. Barrier creams and `Poly Bead' hand cleanser can be purchased at most chemists.

STORAGE: We got a nice new roasting tin from the local hardware shop as we needed a new one, but it was too big to fit in the oven! 16 x 11 inch roasting tin, 15 x 14 oven :-[ So I accquired it :-) I now use it as a `chemical blacking' containment area. keeping all contaminated items in it including the bottles of chemicals in use, just in case it does get knocked over. The tray has now seen a lot of use and looks quite patchy where splashes and minor spills have coloured the metal surface, it is now kept in the workshop well away from all our animals and out of reach of out 2 year old daughter who helps me with some of my safer projects. :)

I use a product called `Perma Blue, Liquid Gun Blue for Steel' which contains Selenium Dioxide, this chemical will `blacken' steel by contact in One Minute, this time is increased to 2-3 minutes for Graham Farish `N'gauge wheelsets, and 3-5 minutes for PECO streamline code 80 nickel-silver rails. Older steel rail only needs 30-40 seconds to look well weathered and one minute for a complete black, usefull in sheds, alongside coal or diesel refueling depots and on pointwork, crossing checkrails, track components etc.. This could also be very usefull when adding a `third rail' saving a lot of painting, although a bit of extra detailing on the sides of the raised power rail with paints would produce more realistic variations in colour and make for a more pleasing model. The photograph (Left) shows how I tied the wheelsets (4 axles) onto a piece of wire for `dipping' into the Perma Blue liquid, I have placed a `New' & still shiny wheelset beside them to compare with. This shows the results of a TWO Minute dip.

Blackened wheelset refitted on an Ngauge Peco brake van, this wheelset was degreased (with washing up liquid) and thoroughly wiped dry, they were then immersed in Selenium Dioxide (Perma Blue Liquid) for about 2-3 minutes, washed/cleaned off using an old toothbrush with a water + washing up liquid then dried carefully. The wheelset was then lightly sprayed with an electrical switch cleaner/lubrication spray, wiped clean and fitted to the model. It is then left upside down until the next day before being released back into service.

The wheels and axles on this vehicle were single dipped and were re-dipped due to a couple of small `silver spots' on one wheel where the piece of wire I used to hold the wheelset in the Perma Blue liquid was touching the wheel and stopped the chemicals reaching the metal. I could have touched up the spots with a fine brush but decided to re-dip them by total immersion in the dip tank giving the wheelset a darker overall finish.

Items made from plain steel will normally turn a very dark Blue, almost Black after about One Minute of contact/immersion with a Selenium Dioxide soloution. This usually gives a reasonable result, but some other types of metal that are not pure steel, high chromium steels, and alloys (EG: Graham Farish N gauge nickel silver wheelsets) require a longer dip time of around 2 to 3 minutes. The dipping process can be repeated a number of times to produce a deeper/harder colouration that will stay black for longer than a single dipped item. It is a good idea to clean the item thoroughly between dips with steel wool or abrasive pads, this will make the item look terrible once cleaned, but dont worry, the next Dip will sort it out and will have a deeper/darker effect the second (or third) time round giving a better final finish. A third dip is required on some alloys to get a good deep finish.

I have achieved good results with N gauge wheel/axle sets, single dipping for 20-30 seconds will give a well weathered, but not quite black appearance which looks good on `old' goods stock. A single 2 to 3 minute dip will give a good black on most wheelsets but I have also tried some with two 2 to 3 minute dips and some with three 2 to 3 minute dips. I am test running Single and Multiple dipped wheelsets mixed on stock on the same train as part of a running trial of their relative durability.

After three months of running comparison trains with single, and multiple dipped wheelset on the same train for durability testing.

Single dipped wheelsets (2 to 3 minutes per dip) and rubbed down with a `light oil' will wear noticeably where in contact with the rail, which gives a good appearance for locos/stock that need the prototypical `thin shiny band' around their wheels showing regular useage.

Single Dipped wheelsets (One 6 minute dip) and rubbed down with a light oil, does not give as good a result as using two shorter (2 to 3 minute) dips.

Double Dipped wheelsets (2 to 3 minutes per dip) and rubbed down with a light oil also wear slightly, but retain a good appearance for Locos / Stock which is used but on an irregular basis, goods stock and vehicles in use infrequently.

Triple Dipped wheelsets (2 to 3 minutes per dip) and rubbed down with a light oil are good for tenders and anything else that requires really black wheels. I am also triple dipping a 4-6-2 + tender wheelset for the LMS Gas Turbine loco I'm building in N gauge but thats part of another project. :)

Wheelsets not rubbed down with a light oil will continue to oxidise, as will the axles, If you wish to model rusty wheelsets on `old' or infrequently used stock, make sure you add a tiny bit of oil on the axle to stop further corrosion of the pinpoint ends, this is easily done with a pin or the end of a small `jewellers' screwdriver. I have also `oiled' the axle between the wheels and it looks the part.

There is a `proper' sealing oil available for use with Selenium Dioxide blueing products, Anyone stocking `Perma Blue' should also stock the `oil' I have not tried it yet but I have had no adverse effects using WD40 (light oil & general purpose lubricant) but will be switching to an electrical contact/switch cleaner without oil, as removing the oil completely is not all that easy but a little warm water with a drip of washing up liquid does the trick. I have had no wheel slip on Stoneybridge with blackened wheelsets which is surprising as I dont think there is more than 2 feet of track thats level, the rest is all gradients & curves.

After over 100 hours running with double-dipped Farish wheelsets they still look good. Some of my heavier stock (IE: Whitemetal & Brass coaches) have worn a thin `not quite so black' line around the contact face of the wheel, which looks quite prototypical and in my view enhances the realism of the models.

Single dipped sets may require re-blacking after 200 - 300 running hours, All double dipped sets are still looking good after intense running, The heavier vehicles have worn a thin light (but still not shiny) band round the running face of the wheel tyres. The rest of the wheel still retains its blackened finish.

I have discovered that the `Cold Blueing' process doesn't actually like the cold! It seems that when I have the window open (beside the desk) the wheel blacking needs two (or three) dips to get a reasonable finish, when the window is closed and its warm in here (the ones I've done later at night) they look decent on the first dip and only some require a second dip, but I am now dipping all my N gauge wheelsets twice anyway, as a single dip is wearing noticeably after a weeks running, whereas all the double dipped ones still look good. I have filed the top edges of a length of code 80 Ngauge track to make them rough (with a large flat file), and simply whizz a spare chassis with a Single dipped wheelset fitted along it several times with a little downward pressure on it, then I attack them with a bit of a brass bristled `ex-loco wheel cleaning brush', clean, degrease & dry them thoroughly, then give them the second dip. after which a little cleaning of a more gentle nature and a little bit of light oil to stop the corrosion going any further. I spray a load of wheelsets at a time with a light mist of WD40 then clean em off & degrease them.. I'm going to switch to using electrical contact cleaner/service spray when I get me hands on some, (when I went to use it, the can was... Empty!) Clean them off with a cleaning cloth or paper towel and bung them on a wagon/coach.. I have left some wheelsets aside without oiling them to see if they will develop decent rust-type ageing effects, I have been helping some along with a bit of moisture occasionally too but nothing useful yet, only the Farish axles seem to rust well, so make sure you put a touch of oil on the pinpoint axle ends before placing the wheelset in the model, if you are going for the rusty old goods wagon look try not to get any oil on the sides of the wheels, but if you do, dont worry as it will only look like exactly what it is, an escaped lubricant, which is prototypical as I'm sure fitters & mechanics wouldn't be too bothered by a bit of oil & grease on some of the many vehicles.

I'm after a decent digital thermometer so I can perform more accurate tests taking temperature into account, until then I'm doing all my wheel dipping in a `Pre warmed' room, IE, not first thing in the morning when the room is cold.

I now have an `Aluminium Blacking' liquid to try chemical blacking processes out on other items such as the alloys soft drinks cans are made of, which is great to make things from but hard to achieve a lasting paint finish on, and of course fine etched detailing components would benefit greatly with all the fine detail being retained instead of being `lost' under a coat of paint. There is also a chemical blacking liquid for Brass, which I will investigate at some point soon. I'm still searching for a chemical or process that will suitably blacken Nickel Silver rod, tube and scale railway track.