MoonMonkey's findings and thoughts

Investigating the problem...
RMWeb (Mick Bonwick) provided insight into the 'Bachmann Tidemark' which is when oil inside the body (and in joins within the construction of the body) is moved through the gap and into the matt powder weathering through capillary action, to form a tidemark.  

 

 

A failure to find Isopropyl Alcohol...
Mick Bonwick's suggestion was to deal with the Bachmann Tidemark and suggested Isopropyl Alcolhol, IPA, rubbing alcohol.  It seems this chemical was tricky to find anyway but had become popular as  cheap DIY sanitizer during the coronavirus lockdown.  The chemists I tried didn't stock it, and I didn't fancy chancing my arm with dodgy chemicals (which may or not have been the real thing) on online market places.  

 

 

My approach...

Step 1...
I therefore washed the entire loco body (after removing it from the chassis) in a mild solution of tepid water and fairy liquid.  Transfers weren't a problem for me - there was no damage to these.  They weren't the original Oxford Rail transfers, they were from Fox Transfers.  I used an old toothbrush to scrub away at the body to remove the weathering and especially around the areas affected, and to scrub the inside of the body.  2 wheel arches (splashers) came away but were undamaged and easy to glue back on.  The brass name plates came off too.  I then let it all dry and glued the items back on.  

My approach...
Step 2...
Once dry, I gave a good thick coating of Humbrol enamel gloss varnish to the inside of the body to seal it and any gaps, so if oil remained or built up due to being sprayed around by the motor, it hopefully wouldn't be able to penetrate through to the matt weathering and have the same capillary action effect to create a tide mark.
Once dry, it was noticeable that a tiny bit of the gloss varnish had itself seeped through, in a few places.  This was fixed with a quick light brush of Humbrol matt paint of a close colour over the gloss enamel varnish - there was no perceptible problem with the paint finish which I gather may occur when applying acrylic over enamel.  Maybe that was due to the tiny area in question. Pics show inside although the gloss varnish doesn't show up.  

My approach...
Step 3...
I the reapplied weathering powder and varnish spray as before, not to any great degree as I didn't want to waste time if the same thing happened.  Upon drying, there was still an oil tidemark in 2 places, notably between the windows of the cab, where it had been worst before. But it definitely wasn't as bad there, and it didn't reappear in the other places again  I therefore concluded that washing in detersives, and a layer of varnish inside, was definitely useful. 

My approach...
Step 4...
I also concluded that if the powder wicks the oil out of the cracks, maybe I could use that to my advantage like spillsorb or fullers earth for the remediation of liquid chemical contamination. I therefore applied a small pile of loose weathering powder (specifically Humbrol smoke weathering powder) and left it for a few hours.  I then took it outside and blew off the excess, and helped the last bit with a cotton bud.  The cotton bud left a tiny bit of scuffing to the weathering powder but not too bad, showing the slightly bumpy mark in the photo in front of the round cab windows.  Importantly, the powder had wicked away the oil.  The other place there was a oil tidemark remaining after round 2 was on the tender around one of the equipment lockers (or whatever it is) on the top I therefore applied a loose pile of weathering powder, left it an hour, blew it away, and the oil tidemark was gone completely.  
I then did more weathering using powder and spray varnish, and was relieved to see there was no more oil tidemark. 

My approach...
Step 5...
After another coating of weathering powder and spray varnish....

Of note, the weathering powder really highlighted the moulding seam along the length of the boiler.  I therefore applied a fine emery wet and dry paper over the seam.  Obviously this left patches along the boiler, but a couple of coats of powder and varnish and these were no visible, the powder covered it up.  

Photos show a before (angled shot, you need to zoom in!) and after shot (side-on shot).... 

I then reattached the bodies to the engine and tender, applied more powder until I got the effect I was after (being careful to avoid getting it into the wheels and mechanism), cleaned the wheels with Humbrol enamel thinners, and bob's your uncle... one weathered loco with no moulding seam line, no oily tidemark and running nicely.  

I did try to clean the powder/varnish of the small windows, using a cotton bud and enamel thinners, but the cotton bud was too big and it started to mark/remove the weathering around the glass in a rather obvious way.  I therefore decided I could live with grimy windows but I couldn't live with messy shabby marks around them, so touched up the powder and varnish, and hope the tiny model crew get their act together and clean them at some point in the future.  

I touched up the handles to the reversing lever and 2 brakes on the tender (or whatever they are) with Railmatch oily steel.  I painted the buffers to include a a bit of a more worn metal centre patch.  It was then ready for crew, fire irons and coal.  

Some photos of what I think is finished... I'm trying to depict a GWR wartime black Dean Goods in late war level of dirtiness, I've based the grey/dust colouring and level of obscuration of the markings on photos of black locos in the 1950s.  

So for my next loco to weather, I reckon I'll give this sequence a go...

 

1. Remove body from chassis.

2. Do any weathering to wheels/chassis as desired (being careful with powder in the motion)

3. Wash the body twice in mild fairy liquid tepid water, allowing to dry after each wash.

4. Apply Humbrol gloss enamel varnish liberally inside... two coats allowing to dry between each. 

5.If gloss varnish seeps through, touch up with chosen colour to match base colour of matt acrylic Humbrol paint. 

6. Apply a loose pile of weathering powder over the body to wick away any oil.  Then blow away to remove, maybe finish removal using a cotton bud or something.

7. Do a simple coat of weathering powder and varnish... check for any wicking / tidemark and if necessary apply another coat of loose powder. Worst case would be to wash again and re-varnish the inside, and repeat with loose powder, until no oil stain appears. 

8. Progress to doing the actual weathering using powder and spray varnish.  

 

I have had the same problem with Bachmann locos although I only weather with enamels.

The first step for me is to dismantle the chassis and get rid of the excess lubricant, Bachmann appear to put 4 times as much lubricating grease as is required. You need to stop the lubrication from being thrown up from the chassis.

i have found that I need to make 2 passes with the Isopropynal and then wash with mild detergent. The lubricant is really difficult to get rid of.

That's a good result! Most impressed with your determination and resolve. You could prevent some of your intended work, though, if you gave the mechanism a jolly good clean first. In the absence of isopropyl alcohol you could use paper towels and cotton buds to remove the excess grease. The grease gets spread around the inside of the body as soon as the mechanism turns the wheels. Clean everything before running it in.

 

For cleaning spectacle plates I find these useful:

 

https://www.scalemodelshop.co.uk/product/50x-small-triangular-cotton-swabs-tamiya-87106

On 29/06/2020 at 23:13, Mick Bonwick said:

That's a good result! Most impressed with your determination and resolve. You could prevent some of your intended work, though, if you gave the mechanism a jolly good clean first. In the absence of isopropyl alcohol you could use paper towels and cotton buds to remove the excess grease. The grease gets spread around the inside of the body as soon as the mechanism turns the wheels. Clean everything before running it in.

 

For cleaning spectacle plates I find these useful:

 

https://www.scalemodelshop.co.uk/product/50x-small-triangular-cotton-swabs-tamiya-87106

Hello, it has taken me a while to get back onto RMWEB in terms of actually logging in, although I have been following threads and looking things up for research... it really is a mine of useful information.  Truly great! 

I thought I'd update on my findings about the oil marks, in case other people find this thread about weathering  locos with powders.  I've used weathering powders for wagons and they were fine and I shall continue to do that. But the loco weathering really is a faff and I think people should carefully think about powders (and how to use them) if they are trying this for the first time.  

Just to recap... I got the results I wanted from powders, but the 'Bachmann tide mark' as explained by Mike Bonwick emerged very quickly.  As per previous posts I thought I'd cracked this by applying liberal coats of enamel varnish inside.  Unfortunately this didn't prove to be the case.  

Not long after my previous post (29th June), the tidemark reemerged.  I thought this might have been because I tipped the loco onto it's side when moving it or something, but no, it was running that seemed to be the problem.  The tidemark emanates from the gaps and not not just the large open area between the boiler and the 'wheel arches' (splashers?).  For example, the tender has a tidemark too.  Granted, the tidemark didn't appear at the to around the cab roof this time, but it is still pretty bad elsewhere.  I reverted to my previous approach of absorbing the oil with powder.  I used this like spillsorb or the kind of powder or grit used for chemical spillages (or spilled petrol at the filling station).  I brushed on a liberal amount over the affected areas and left for a while... about 1 hour.  I then carefully hoovered it off using the extension nozzle and assisted with the brush to work off the powder that was a bit fixed.  I was careful not to get powder into the motor and running mechanism if I could help it.  This seemed to do the job, although the engine/loco was a little more dusty, but that probably happened with the prototypes... a progressive build up of dust and dirt.  For those who are interested, I used the Humbrol smoke weathering powder, so any residual powder left wouldn't look too out of place. As far as I recall, I didn't apply spray varnish as (a) there was no real excess of dust left, and (b) it didn't seem to seal the powder against oil in the first place.   Photos of before and after attached... 
 

I then went away which involved the model going into a box for 3 weeks, noting that it was the right way up and not in sunlight or damp or anything like that.  When I took the thing out of the box... guess what?... another tidemark.  I shall try the same method again.  Photos of the tidemark also included here.  
So, in summary, what a faff!  The powder with acrylic spray varnish looks good, but the oil mark spoils it.  It is fixable in the short term by using (an appropriately coloured) weathering powder like spillsorb, eg if you wanted to take some photos, but the oil stain is likely to come back.  This may because I used the powder like spillsorb and may not have sprayed it again - if I didn't use varnish then it would be capillary heaven.    
I shall have another go at applying the powder again for this loco, and I shall use a varnish spray this time for sure.  But who know's how many times this needs to happen before the oil reduces enough to prevent the splashing by the working parts and subsequent capillary action through the joins?  It might be that a different kind of varnish - not acrylic -  might fix the powder and seal it against ingress, but I doubt it, and presumably that would seal in the oil to the varnish even more.  I see on threads like Little Muddle that powder is used along with the trusty Dullcote before and after... presumably this is less porous than the acrylic spray?  
I think I shall stick to washes in future.  If I ever learn how to use an airbrush, that would seem a a sensible method for weathering too.  
But unless I learn the secret to successful loco weathering with powders, then I shall avoid it for expensive / precious locos like the plague.  I'd rather gorge myself on bourbon biscuits for three weeks and then attempt a cross-channel swim while wearing a swimsuit made of fishfood.  

Photos of the current state attached to show the tidemark has returned!...

Why not abandon weathering powders and just weather with enamel paint?

13 hours ago, Brassey said:

Why not abandon weathering powders and just weather with enamel paint?

Hi Brassey, agreed... in future I'll stay away from weathering powders for locos, unless a foolproof way becomes apparent.  It'll be paint for these kind of jobs in future.  

I'll keep the Dean Goods 'as is' though rather than stripping it back and rebooting.  I'm intrigued to see how it fares with occasional application of loose dust when it needs tidying up.  

Morning Monkey chap.  

 

I only use powders and have also experienced the oil thing. 

 

It really is a question of cleaning and cleaning prior to weathering. Bachmann is not the only offender as I have had Hornby locos with the same issue and have adopted a similar approach to you by applying matt varnish to the insides. I also spray the body using matt acrylic varnish as a base coat for the powders. Care is needed as this can lead to too good a key for the powders which don't always spread about as they would on a factory finish. 

 

However, it really does come down to cleaning prior to starting. 

 

I prefer powders to the alternatives. I find them easy to work with and, for me at least, provide the results I want. Nothing matches it for texture and ease of blending...........in my view. 

 

Rob. 

Hi Rob, thanks for the info.  I love the picture... just the look I was hoping for, and I agree about the powders being user friendly.  Is that an oil tide mark on the back above the buffer beam or intentional weathering?  

 

Do you clean with that IPA stuff (not the beer) or something else? 

 

It's interesting that not all brands seem to have this issue.  I have a Heljan tank engine that I'm looking to weather next, and also a Dapol flying banana that I want a very light dusting around the bogies and lower faces.  Have you found that any brands consistently avoid this issue? 

Hi Monkers 

 

It's a bit of dark earth/black shading  across the top of the buffer beam /lamp irons which appears darker in the above photograph. 

 

I clean using thinners and a small amount of  auto cleaners (tested on plastic first) using cotton buds. I tend not to apply the weathering straight away but leave things until I'm sure it's clean.