Some simple tips for weathering with an airbrush...

Discussion in 'Weathering Forum' started by doctorwayne, Mar 5, 2007.

  1. doctorwayne

    doctorwayne Active Member

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    Some paint schemes require that you mask parts of your model in order to apply additional colours with your airbrush. Usually, masking tape is used for this purpose, as we want the colour separations to be very distinct. When weathering cars or locos, or even structures with an airbrush, sometimes a colour separation is also required, but, in general, the colour separation should be more gradual. An easy way to accomplish this is through the use of homemade masking devices.
    A good (and inexpensive) material for this is boxboard, the stuff that cereal boxes are made from. It's stiff, but not too thick, and easy to cut with an X-Acto knife.
    Here are some examples of easy-to-make and easy-to-use masks. Just remember that your weathering paints should be thinned to a greater degree than you would for regular painting. Using Floquil as an example, I use about 30% thinner for most painting, but up to 90% thinner for weathering colours. It's much easier to make multiple passes to get a darker effect than it is to try to lighten the effect of weathering that's too heavy.

    This one is useful for adding stains or streaks beneath a detail on any model.
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    The narrow slit will give a narrower stain, obviously, but the effect of both slits can be varied depending on how far away you hold the mask from the object being sprayed. Place the mask so that the top of the slit is immediately below the object from which the stain originates. These are good for making rust streaks below protruding details on a carside, such as the stop at the end of a doortrack. They're also useful for making the slight discolouration on building walls beneath the ends of window sills. I used the mask pictured above to make the black rust discolouration beneath the band tighteners on this Atlas water tank.
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    The rust stains on the wall where the support rods for the platform roof on the right are anchored were done with the narrow slit, held slightly away from the wall.
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    This one is similar to the first, but the slots are designed for use with wider protruding objects, such as smokejacks on sloped roofs.
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    This one is made from styrene, but boxboard will work here too.
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    It's for putting wheelspray patterns on the ends of rolling stock and locomotives.
    Here it is in use:
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    And the results. The jars of various colours of paint are to the left of the car upon which they were used. All of these were light applications: older cars could be weathered more heavily in this area.
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    Here's a really simple mask: the corner of the cut-out could also be rounded, if you prefer. This is for making exhaust stains on diesel roofs.
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    Spray should be directed from the open side of the mask, towards the exhaust stack. Here's what you get from one spray:
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    As you use this mask, keep turning it, so that the open edge faces, in turn, to all sides. You can spray a little more at the ends of the stack than to the sides, and even more towards the rear if the loco travels predominantly in one direction, like an E- or F-unit.
    This is a fairly new loco, so the effect is kept to a minimum. On an Alco, the exhaust pattern would usually be much heavier and more widely distributed. Btw, I used a brush to paint the interior of the exhaust stacks before spraying.
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    Here are some more specific masks, each one cut to match a particular car by a particular manufacturer. Occasionally, different cars can use the same mask, with minor adjustments for the door size. I write the specifics of each mask right on it, although it might have been better on the reverse side.:rolleyes: I usually use these in conjunction with washes, sometimes before and other times, after. I prefer a dirty black or dark grey, but other colours can also give interesting results. This one is for an Athearn 40' boxcar:
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    A Train Miniature X-29:
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    A Train Miniature plugdoor reefer:
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    Another simple technique is shading. In the first picture, the jar of paint on the left is the thinned colour used to paint the car. The jar right next to the car contains some of the same thinned paint with a bit of other colour added to it: the choice of colour added isn't too important, as long as it slightly alters the appearance of the paint. The jar with the altered paint in it will be filled with thinner before I begin applying it. The car is painted, and has had a very light wash applied, but has not yet been spray weathered.
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    I'm using a mask made from matte board, which explains the odd texture. Hold the mask against the car, on a seam or rivet line, then make one pass, spraying towards the area where the mask meets the carside. Be careful to spray from the bottom edge of the car, to avoid getting too much on the edge of the roof. I've folded a couple of business cards to cover the truck sideframes and yet leave the drop steps exposed. This helps to tilt the car, further protecting the roof area. Do each panel line on the carside: you should usually reverse the placement of the mask on the opposite side of the door, as the panels are usually lapped either towards or away from the door on both ends. The two panels at the end have been weathered, while the one next to the mask is as yet undone.
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    This greenish gunk has been applied to the shaded car, mostly on the trucks and underbody. Because it's mostly thinner, any overspray has little effect on the carside, other than to darken it slightly. For this kind of weathering, the car is on a piece of 1"x4" in the spray booth. I drop the wheels on the near side of the car over the edge of the board, then use my free hand to roll the car back and forth as I spray. This ensures that the wheels turn, preventing any one area from receiving too much weathering while another area receives none. The spray is directed slightly upwards, from below.
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    Using the same technique, but a lighter colour of thinned paint, highlights details on the trucks and gives a light coating of road dust to the lower car sides. The spray is kept fairly low, but sprayed directly at the trucks and lower body of the car. I've kept the weathering light on this car, as it represents one less than two years old.
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    Another way to weather a car subtly is with a heavily thinned application of the basic body colour. This Red Caboose reefer has had a light wash of black PollyScale, followed by an overspray of the basic body colour. Vertical strokes with the airbrush work best, especially on a wood car, where individual boards were often replaced. Don't hold the tip of the brush too close to the car. This technique softens the lettering, and is useful for any car that does not represent a brand new paint job. If the roof is a different colour than the carsides, as on this reefer, use masking tape or a piece of cardboard to shield the roof edge.
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    To weather locomotives, rather than placing them on the board in the spray booth, I use a piece of track on the bridge of an old Bowser turntable. Clip a pair of leads from a power pack onto the ends of the rails:
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    Place the loco on the track, and turn on the power so that the wheels turn at a medium speed while you hold the loco with your free hand. Now, when you spray the trucks and underframe, the entire face of each wheel will receive the same amount of weathering. I usually let the loco work its way to the end of the track as I hold it while spraying, then drag it back to the other end while not spraying. This trick will also work for steam locos, for painting the drivers, and siderods and valve gear, although you'll still need to clean the wheel treads afterwards. If you're applying heavier weathering to a diesel, you may have to clean the wheel treads, too. This one represents an almost new one, so weathering will be light. I'll refrain from showing the finished product, as the loco belongs to cn nutbar, and he's not yet seen the finished job.
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    You can also create the illusion of more detail with a couple of simple airbrushing techniques. In the picture below, the building on the left houses the stairway for access to the overhead crane. It's a simple box, made from some milled basswood corrugated siding that I had laying around. I wrapped some masking tape around it at measured intervals where the upper panels would overlap the lower ones. Starting at the lowest tape, I sprayed some "rust" along the lower edge of the tape, to represent the rust that "bleeds" out of the cut edges of the steel sheets. When the lowest seam had been done, I removed the tape for it, then went on to spray the next level up, until the structure was done.
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    I did the same thing to this structure, even though it does have individually applied sheets of siding. To avoid damage to the delicate sheets, rather than use masking tape, I simple held a piece of cardstock over the bottom of each row while spraying the top of the sheets below it.
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    This also worked for the roof of the carshops at Lowbanks, lower right, below. While there are two separate rows of corrugated roofing, most of the rows are not individual sheets, although a few were included, to enhance the illusion that the entire roof was made up of individual sheets. (On the prototype, well-applied corrugated siding will cast a slight shadow on the row below, but the individual sheets are not distinct until they've begun to rust. Even so, most modellers apply them much too sloppily to act as an effective deterrent to the elements.) I used a piece of cardstock to spray delineations between the separate sheets that aren't actually modelled (and the few that are, too).
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    Finally, in the picture below, I used masking tape, applied with less than a scale foot between their edges, to represent roll roofing on both the small icehouse in the foreground, and on the red coal shed behind it. I airbrushed a reddish-brown, well thinned, and on an angle, aimed "up" the roof, so that the spray caught the lower edge of the tape, leaving the lower edge softened like run-off, then the tape was removed. The coal shed, with its dark grey roof, got the same treatment, using an even darker grey.
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    If you've waded all the way through the foregoing, I hope that you've found some information useful to your modelling endeavors. If you're unsure about some of these spray techniques, practise on a piece of corrugated cardboard, until you're comfortable with the operation and satisfied with the results. If you first paint the cardboard the colour of the model you're planning on working with, it will also give you an opportunity to see the different results possible simply by using a different colour of paint for your weathering.

    Wayne
  2. joesho

    joesho Member

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    wow,thats very usefull,thanks for posting that wow thats alot of info great job :D
  3. liven_letdie

    liven_letdie Member

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    Wow...just wow. Thank you so much. This is very much appreciated.
  4. Herc Driver

    Herc Driver Active Member

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    That is great information and techniques. Thanks for sharing!
  5. doctorwayne

    doctorwayne Active Member

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    Thanks, guys. I'm sorry that these cars may not be the best examples to show weathering, as most are meant to be either new or quite current to their era. Some of the more weathered cars shown in a couple of photos were done using the same techniques, although carried much further.
    I also have a set of photos on applying washes, which I'll try to post later this week, in a separate thread. Unfortunately, the pictures use the same cars, so the effects are somewhat understated.
    That said, the key to using these techniques is that the paints you use for weathering be thinned severely. If you want a dirtier car, make more passes with the airbrush, and, as I said, practise on cardboard or something similarily cheap. Then, when you feel competent to try an actual model, start with a real cheapie. I've been doing custom painting, in addition to my own stuff, for about 30 years, and I would rate myself as fairly competent, but I am no artiste as far as airbrushing is concerned.

    Wayne
  6. MasonJar

    MasonJar It's not rocket surgery

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    Wayne - excellent work! Thanks so much for the complete run-down. It makes me want to run out and get an airbrush and spray booth - or send all my models to you for a "tune up" ;)

    Andrew
  7. Iron Goat

    Iron Goat Member

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    Thanks Wayne, for the excellent information... that answered quite a few questions for me.

    Bob
  8. Gary S.

    Gary S. Senior Member

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    DoctorWayne, you are a genius.

    So far, I have been avoiding buying an airbrush, but this technique makes me want one.
  9. bigsteel

    bigsteel Call me Mr.Tinkertrain

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    thank you so much,i can finally USE my airbrush :D .--josh
  10. Biased turkey

    Biased turkey Active Member

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    Thanks doctorwayne for explaining your "inverted vees" technique you mentioned in a previous thread. Now I can see how it works.
  11. doctorwayne

    doctorwayne Active Member

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    I probably should have mentioned that the bottom edge of the "vee" masks should line up with either the bottom edge of the car, or the bottom edge of the car's sidesheets, as any exposed area below the mask will get fully weathered. After using these masks, I usually spray the lower carsides with a different colour of road dirt, so as to soften the colour transition.

    Wayne
  12. EngineerKyle

    EngineerKyle Member

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    Thanks so much.