TEXT: F
  orge World weathering powders offer a very versatile way of 
  adding new painting effects and detail to your models and 
  can be used in lots of different ways. This quick guide offers 
  some advice on how you can use weathering powders and the 
  kind of effects that you can achieve. 
  Weathering powders can be most simply applied as a dry 
  powder with a brush, and it’s very easy to blend and stipple the 
  weathering powder onto your painted models in this way. When 
  you are doing this it’s important that you use a clean brush (the 
  Citadel Small Drybrush is a good size and shape for this.) The 
  effect you can achieve using weathering powder in this way can 
  be very vivid and strong, so it’s best to apply small amounts of 
  the powder at a time, particularly if it’s your first go! 
  Once on the model the powders create quite a resilient finish, 
  however if your models are going to be frequently handled 
  (which if your going to game with them is fairly inevitable!) you 
  might want to seal and fix them in place with a light spray of 
  matt varnish after they’ve been applied. 
  FORGE WORLD WEATHERING POWDERS
  The model was first painted Desert Yellow.
  The model was then lighly drybrushed with Kommando Khaki. A 
  wash of Gryphonne Sepia was applied to the model. To represent 
  chipped and scratched metal a fine sponge was used to dab a 
  mixture of Scorched Brown and Chaos Black onto the edges of the 
  armour plates. 
  Using a Detail brush Dark Earth weathering powder was then 
  brushed onto the armour plates to weather the model.
  Black Soot weathering powder was brushed in-and-around the vents 
  to simulate the discolouration that exhaust gases would create over 
  time.
  To finish and seal the 
  weathering powders the 
  model was sprayed with a 
  coat of Matt varnish.
  
  A side panel of a Leman Russ was painted Catachan Green, again it 
  was weathered and chipped prior to applying the powder.
  An old brush was used to randomly sprinkle Light Earth and  Dark 
  Sand weathering powders onto the model.
  White spirit was then touched onto the surface of model and 
  allowed to flood over the armour plates naturaly, care was taken not 
  to actually move or disturb any of the weathering powder with the 
  wet brush itself.
  Once the wash of White Spirit 
  had completely dried on the 
  model, the clumps of weathering 
  powders were blended into 
  the surface colour of the 
  armour plates with a clean 
  small brybrush, and dragged 
  downwards to form streaks.
  Again, to seal the weathering 
  powders the panel was given a 
  coat of Matt varnish.
  
  Once you’re familiar with weathering powders, there are a 
  number of other methods you can use to achieve some different 
  kinds of appearance and layering of detail. You can for example 
  apply them to the model’s surface and then use a liquid such 
  as White Spirit painted over the powder to create some differ-
  ent effects, streak and fix the powders. Once this has dried the 
  powders can then be further blended to enhance the effect. You 
  can also apply the powders wet by mixing a thinner in with them 
  (such as water or White Spirit) you then can apply them just 
  like paint or a wash, and when they are dried you can further 
  blend and streak the powders 
  to 
  deepen the effect to create ageing 
  etc. You can even can mix the 
  powders with Citadel paint to cre-
  ate textured effects such as thick 
  mud or heavy corrosion, (but 
  make sure not to use your best 
  brushes, as this may wear them 
  out quickly.) 
  You can find some more details 
  and examples of the use of 
  weathering powers in our 
  book Imperial Armour Model 
  Masterclass.
  Forge World weathering powders are available in a variety 
  of earth and rust colours, and can be used to create a wide 
  variety of effects such as desert sand, ash and mud as well 
  as corroded and battle-scared metal. The powders can also 
  be mixed to provide your own unique tones and shades. 
  This Imperial Guard Chimera side panel was 
  given a heavily rusted appearence using 
  Orange Rust weathering powder around the 
  raised edges of the armour plating.
  Extra layers were applied around rivets and 
  other surface details to represent the most 
  severe corrosion. 
  Once more, to seal the weathering powders in 
  place a coat of matt varnish was applied.
  
SOURCE: textdata/thevault/Crafts/Painting/Warhammer Specific/forgeworld-weathering-powders.pdf