Patchy

Over on the Scalefour Society Forum, I have asked about the use of metal black as a preparation for painting, and these are my experiences...

Well, firstly, I started off by giving all of the parts that were going to be treated a good going over with Carr's Acidip to chemically clean the surfaces thoroughly, and to get rid of any traces of flux, dirt and so on. After this, it was into some plain water in my wife's jewellery cleaning ultrasonic tank...

This always does a superb job at making any remaining grime and noxious substances literally fall off the model. You can even see the slightly cloudy water streaming away from the model when you switch the machine on. And she is happy as well if you offer to clean her rings at the same time - although preferably without the application of Acidip!

After this, the parts were popped on some kitchen paper in a box to keep the dust off them and left to dry thoroughly in the sun. Such are the joys of modelling in the summer.

After this, I reached for the Casey's Gunblue, and applied it with the end of a cotton bud. Unfortunately this was the result - distinctly patchy.

I'm not quite sure why. The model wasn't handled at all after cleaning, and was perfectly dry. I can only hypothesize that it was variations in the grades of nickel silver that made the difference.

Either way, I followed it up with a thin coating of etch primer, sprayed on, to ensure that the paint would adhere properly. I'd washed the remains of the gunblue off with plain water so the surface for the primer was clean again.

So quite a disappointing result. I still see the merits of using blackening on the edges of models to ensure that any paint chips won't be so obvious. That makes a lot of sense, and I'll be doing it in limited circumstances. I also suspect that the gunblue will "take" better on brass than on nickel silver, so I haven't given up all hope of this method.

I thought that I'd post the results so that you can all see what the outcome was, and perhaps add your own thoughts or experiences.

Don't try this at home...

...or anywhere else for that matter.

As part of my P4 demonstration track, I've planned to show various different types of trackwork construction.  A rough plan of it shows what I mean:

 

Part of it is to link a P4Track Company B8 kit into the three-way point made from ply & rivet.  I'd made the B8 a couple of weeks ago without problem.  Last night I finished riveting the ply sleepers, a tedious task at the best of times, and started laying them out on the template:

Unfortunately, when I looked at it the difference in height between the plastic sleepers and ply sleepers was more significant than I expected:

I'll just have to work with that, laying the ply onto a thick card trackbase.  Once bitten, twice shy, and I'll not attempt to mix the two types like this in future.  I recommend that you do the same!

Also, the act of laying down the sleepers showed that I'd missed out punching and fitting one rivet.  It's right in the middle of the point, at the end of the wing rail.  I thought momentarily about making another sleeper, but then realised that I could just use one of my spare P4Track Co. plastic chairs to fix the end in place.  

So that's a solution that saves the situation and will produce a good cosmetic effect.  Next stage is to start making the crossing vees.

In the raw

I thought that I would make a final post of the chassis construction for the Pug.  The reason for doing so is that this is the last time that it will be seen in this state of raw metal.

The next instructions ar "break the chassis down into its sub-assemblies [done, as you can see] and paint it".  So I lose all of that lovely shiny nickel silver, and start to gain something that looks like a proper locomotive :-)

In case you were wondering about the slightly mangled looking brake gear, it isn't broken or mis-assembled.  Chris at High Level has used a very ingenious design to make the entire brake gear removable from the completed chassis.

There are "carrying tubes" that run through the chassis frames, and through each of these passes a loose wire.  From this the soldered up brake rigging hangs.  The fact that it is soldered means that it all stays in alignment with the wheels as a single unit.  The seemingly misaligned wire at the far left is actually just one of the loose mounting wires that I hadn't tucked properly back in place.  You are even told to put a slight curve in the length of the mounting wires to ensure that friction holds them in place.

I've yet to see the instructions for final mounting of the brake gear, but I may well put a small blob of black paint on the ends of them to fix them securely, yet in a manner that can be easily detached, for extra security.

In the meantime, it will be off with the wheels, a final clean in the ultrasonic bath, and into the paintshop...

And then there were two

Brakehangers that is.

This was the brakehanger that remained, and I wished to copy.  The scrap nickel silver is a OO spacer from the kit, so the correct thickness and also surplus to requirements.

I used my Resistance Soldering Unit to attach the hanger to the scrap.  Using a RSU was ideal for this, as I could "spot weld" the parts together and no risk the completed brakehanger de-laminating or otherwise losing parts. 

I then took a piercing saw and fretted around the outline of the master and whilst they were still soldered together used the holes for the brake rodding to drill through into the new part to get them properly aligned.  When this was done, I carefully slid a scalpel blade between the old and new components and gently heating them with a conventional iron split them apart.

All that I had to do after that was to drill a small hole in the centre for the piece of wire to represent the brakeshoe  retaining pin, and solder in a small piece of wire.  Unfortunately at this point a no.78 drill was lost in action, but we all get casualties from time to time.

A spot of cleaning up with a file and these are the finished articles.  The re-manufactured one is at the front.  Not quite as neat as the original etching, but the day has been saved :-)