corrugated roof rust technique help

edited December 2013 in Techniques

Hi guys I've been working my way around with the Rembrandt chalks and really feel that I'm failing miserably on the corrugated roofing to try to get a nice worn rusting look. I thought I'd come in and see if I could get some tips from you guys that utilize Bretts rembrandt wash technique.
The steps I took to getting to what I have here are I first primed the metal roofing with grey primer and let sit over nite. I then painted cut up and glued the sheets on the roof using canopy 560. I then gave a coat of 99% Alcohol mixed with waterproof India ink. I then applied the chalks one color at a time on the roof pulling them upward with the clear 99% alcohol. I'd wait and move onto another shade mostly experimenting The order in which I applied are from the top down in the photo.
I found by the time I was done the paint under the chalks was bubbling up more on one side of the roof then the other so I got my pencil wire scarper and pulled off the chalk and gave a fresh coat of polly rust ( not sure if it will stick to the bare metal or not but thought I'd try anyway.
Guys is there a proven sequence / technique to get a nice colored rusty corrugated roof?
Thanks in advance


before chalks added

After chalks added


  • edited December 2013
    Firstly Lynn it's great to see you posting some of you work here, even though unfortunately it's not a SierraWest kit ...... :-)

    I guess we'll let you off this one time as you are asking about a technique and we can only see the roof.

    There are however a couple of issues with answering your question...

    Firstly you seem to be mixing several techniques from various sources/manufacturers in getting to the point you are at. This is causing you to have several problems.

    Alcohol should be mixed with NON-waterproof ink, otherwise it wont mix properly.
    Not sure where you got the canopy560 glue idea from, regular wood glue works fine.
    If you colour the panels prior to gluing them to the roof you will avoid having the base colour showing through between the panels and under the overlaps.
    The alcohol is attacking your base layer of paint when you are applying the chalks wet, the chalks should be applied dry. This wash technique is primarily used for colouring wood.
    The poly paint will not stick well to the bare metal and will likely come off leaving shiny spots.

    Secondly you haven't provided a goal for us as to where you want the roof to end up.

    There is definitely a proven sequence or two for corrugated roofs, you just need to decide which result you are aiming for and take the appropriate steps, this is where we can help you.

    If you can find a picture of a roof that you would like to emulate here on the forum in one of the build threads or on one of Bretts models on the website I am sure the builder will be more than happy to explain how that result was achieved or one of the other members will be able to help you with the technique.

    I look forward to seeing what you are aiming for, of course it would be a lot easier helping you with the technique if you were working from the manual.


  • Thanks Karl for taking the time to post. I will be doing Bretts two beginner kits very soon I'm just trying to hone my skills first. I'm also looking to removing my walthers plastic three stall roundhouse and replacing it with Bretts Loco Shop very soon, I only wish it was a two stall.
    I can't say that I knew that the chalks/alcohol method was only for wood. I do have a couple bottles of Higgins non waterproof india ink coming by mail, Michaels was out. Which is one of the reasons I haven't started the sierra kit.

    Since first posting I went back to the drawing board working off the pallet I have ( original roof ) and building up the layers learning as I go , seeing the results one color on top of another as well as what mixing a dark orange and burnt sienna will do. I also found that blending the powers and using less alcohol on the brush gave more controlled results in a more defined area. But now that you say the chalks should be used dry and probably in a certain combination of layer build ups I'll have to try it.
    I've searched quite a bit for the right rust look but haven't had much luck. I'm not looking for a etchant type result or I would just dip the panels in etchant and be done with it, I'm more looking for a nicely rusted roof that is not decaying but definately rusted and discolored. Will have to do some more searching.
    This is where I'm at right now. I took these photos with low light and no flash of course.


  • Lynn,
    when you start your SierraWest kits you will see that Brett's manuals will teach you everything that you need to know to complete those kits, including the required weathering and colouring techniques in great detail.

    Sharing those SierraWest builds here will get you some good advice and/or help if you need it.

    Chalk and alcohol is not only for wood, it is a very versatile and broadly used combination. There are many different ways we use these items. The various techniques for C&A and where and when to use them are explained in the manuals.

    Hope this helps,
  • Thanks Karl its a learning curve that I've been enjoying.
    See you in the modeling world.
  • Hi Lynn - I am a newbie at this stuff. I posted some photos of my corrugated roof and techniques under the o scale woodcutters removable roof thread with the products I used. Hope that is of value ...
  • Thanks James I'll take a look read.
  • Good Evening Guy's. I just thought I would like to share this with you,I am working on the roof of the engine house and here is what I do before install them.P1030288
    After I cut them I use two sided tape and then take this roller to make them stick better and flatten them out it is a roller for laminated floors.
    I wash the sheets with Final Wash.



    Then I spray them with this self Etching PrimerP1030294

    The end result gives a nice gray look and the primer on the panel sticks better. Then weather as you like


    Hope that this helps it is no fun when some of the paint chips off while working the roof
  • Is there a difference between self etching primer and regular automotive primer?
  • Lynn . This will work best on aluminum it will etch in to the metal.
  • Lynn Mikemettelka may be of some help here he is a auto body man and he could know more about it I have been using it for years. .....Carl
  • Self etch is different in that it has zinc and phosphorus in it.
    Self etch primer is for metal that has not been etched by some other means. So if you are building something or weld up some brand new sheets of the steel and do not want to sand them you use the self etch primer. The job of self etch primer is to make a good surface for putting the next layer of paint on to the metal. If the metal is already a good surface for a direct to metal paint then you do not need (and do not want) an etching primer.
  • Thank You Mike I knew that you would know. .........Carl
  • Hope this is the correct discussion to use. I have screwed up more corrugated and seamed aluminum roofing than most of you have owned. Attached is a mea culpa as well as a question. What has worked best for me (attached) is etching (ferric chloride). I fear that it is irresponsible in a chemical way - what think you? This technique will reduce the metal to lace is you're not careful, and sexy though that is, the boss points out, correctly, that working structures should be allowed to have roofing that is severely damaged.

  • should NOT have severely damaged roofing
  • Nice looking corrugated metal roofing. The aged coloring is subtle and effective. Nice modeling detail on the shed roof with the hammer and box of nails.
    Is your corrugated roof ridge cap homemade?
  • I like it.

    The roof under construction is neat. How about some more shots of that?
  • Okay, one more roof photo.
    Please let me say again, ferric chloride is nasty stuff. It generates hydrogen gas and is quite exothermic when oxidizing aluminum. Use it outdoors, wear gloves and eye protection, and FOLLOW the included directions.
    The preferred SWSM techniques for weathering roof panels work exceptionally well and are entirely safe. Do try them before experimenting with weird science.
    The cap is from the raised seam aluminum in the kit per instructions.IMG_0859
  • Precautions are absolute and well stated but with great results.Timing is everything as well. I've had pieces completely dissolve before I could get them back out of the ferric chloride and neutralized.
    Baking the primer is the secret with Brett's newer technique. Rick
  • I agree that the echant gives a nice effect, but as stated it is nasty stuff and needs very careful attention to safety procedures. I really didn't like using corrugated metal roofs before I started using Brett's priming then baking the metal technique. I would always get shiny spots where the paint would brush off. The baking really adheres the primer to the metal with almost no shiny spots.

    After priming and baking I use acrylic hobby paints to weather the panels. I use 3 or 4 rust colors lightly damp brushing them on in succeeding lighter colors. The last color I use is black that is very lightly dry brushed on the panels.

    I don't use a lot of chalk as I think it too uniformly covers the panels. I like the streaking I get with the damp/dry brushing. There is no right or wrong technique, just what works for you.
  • thanks tom, i'll have to try that on my next corrugated roof.
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