By John Adelmann (Fine Scale Modeler, February 1997)  

In spite of a respectable painting work and good decals, sometimes to an airplane in scale lack realism, and the details remain hidden. This is a technique that will not only emphasize the details of the surface, but that in addition offers a perfect control of the dirt without damage the painting work. Is also applied in the scale models with lines of panels inside as outside (or raised and recessed panel lines). It is necessary for this painting technique enamel paint (synthetic) and acrylic gloss varnish (Photo 1).

Also we need a mineral solvent (turpentine spirit) and a piece of cotton fabric that does not loosen threads (it can be of an old t-shirt). We have chosen the scale model of the Super AH-1W Cobra in 1/35 scale to demonstrate this technique because it has raised panel lines like details recessed.

Paint and preparation

After gluing the model and preparing the surface, sandpaper all the imperfections with a fine grit. It is necessary to consider that this process of aging darkens the bottom colors. In order to compensate we will add white matt paint when we paint with each one of the colors of the camouflage. We must experiment first to find the tone wished; the proportions used in this occasion were one part of color and one part of white. Remember the proportions of mixture in case it must prepare more painting for adjustments. After painting the outside, interior, helicopter rotor blades and armament, dand off the imperfections in the painted surface with very fine water sandpaper (1000-1500), and retouch with paint if it necessary. Review the model with a rough fabric to clear the dust over it.

Gloss Varnish

Now varnishes totally the model with the gloss acrylic varnish. You can use any acrylic varnish with watery base. This acrylic varnish layer comes up that the painting of the model is affected by the washings with enamel paint that we are going to apply to it. Be sure from which the airbrush is clean before giving the coat of gloss varnish and clean it again after using. Dilute the varnish with a 40% of water and one drop of detergent to improve the fluidity. Apply several fine coats to form a good varnish layer, being left to dry it approximately one hour before applying the following coat. Also cover the flight edges and attack borders of the wings and ailerons. Resist the impulse of apply the decals.

Washings

The washings are make with a diluted black enamel paint solution and dark brown, both gloss, this must to that synthetic or enamel shining extends more than the matt colors. The washing must be diluted in its right point to be able to penetrate quickly within the panels lines. If it is diluted a little it will slide slowly within the panel lines, and if it is it too much not will notice the effect that we are looking for. Experiment to obtain the best results. As it is advancing in the work the washing will slide more and more slowly, and will need to add more solvent. Possibly it will have to make a new mixture of the components; take note from the proportions of each one so that it has left equal. With a fine brush carefully applies the washing in all the recessed panel lines (Photo 2),specially in the encounter of panel lines. By capillarity, the washing will run through all the lines. The long lines of panels will require additional applications. It does not drag the brush throughout the lines, only touch it slightly with the tip of the brush loaded with the solution. Apply washings to all the ailerons,  access panels and blower pipes. Non loading too much the washings of once within the deep lines, like the hinges of ailerons or flaps, because it can cause that the solvent attacks the base acrylic varnish, because more amount of solvent takes more time in curing. You can abundantly stain the model until find the just point. After each application leave it to dry well, can add washings later if you wishes it. Deal with not applying too much in the flat surfaces, but not worry if this happens. Does not clear the washing until it is completely dry, even though has committed a mistake or applied too much. It can fix it after which it has dried. Carefully apply also the washing in the raised details (Photo 3).

Like the recessed details, the raised panel lines and other projections benefit with the capillarity effect. The washing is attracted towards into the corners and edges, and remains there until it is dried. When it finishes, lets dry the model at least by 24 hours. The model is seen now quite dirty, but do not worry for that reason, in just a short time it is going away to see better. What is good for the outside is it also for the interior. Also apply to gloss varnish and washings to all the internal molded structural details (Photo 4).

Cleaning

After the model has been dried for a day, it is time to clear the excess of the washings. Put a clean cotton rag around its forefinger and applies clean turpentine spirit with a dropper (Photo 5).

 After you has wet the rag completely, carefully clean the excess of washings from the front backwards, in the air flow direction (Photo 6).

Do not rub too much or it applies much pressure in any place, and do not pass it in circles. Only do two or three last ones in an area per time, and soon changes to a clean part of the rag. For those places difficult to clean, applies a drop of turpentine spirit to a small brush, and soon pass it in the difficult places, and soon clean it with the cotton rag (Photo 7).

Remember that it must leave dirtier around the engine exhausts and the flight surfaces. You can add more solvent to treat the most resistant spots, but do it carefully. When you has completed this step, your panel lines and raised details will look like in the Photos 8 and 9.

What amount of dirt must remain depends on you.

A step further

The worse thing than can happen when implementing this technique is that the solvent transfers the acrylic varnish layer and removes part of the color; if this happens, not leave in panic. Let dry well the model, carefully sand it and equals the surface with the around painted surface. Repaint, varnishes and applies the washing again. You will have to calculate how much varnish to apply, how much solvent put in the cloth and how much pressure use to remove the excess of washing. The key is the practice. There is a point in which the solvent does not clear the washing. Not penetrate the varnish layer, masks the problem area and applies a light layer of color with the airbrush. Soon apply varnish on the new painting. After which the model is aged and all the excess of washing was removed, review all the surfaces looking for marks of drops or splits of solvent, and soon apply light coats of varnish to seal the surface completely. Let dry the model by a few hours.

Little pieces

This technique can also be used in the small parts. In the case of the Cobra, it has been painted, varnished and applied washings in the Hellfire missiles, the TOW missiles and throwers, the engine and the details of the cockpit interior (Photo 10).

The technique of the dry brush also aid here. This is a technique to accentuate the raised points. Was used an old brush with silver color paint, and after clearing almost all the pigment in a piece of cloth, the small amount of pigment that remains in the brush can be transferred to the points in relief with sweep movements of the brush. This gradually brighter the piece and adds aging to the raised edges and points (Photo 11).

A good example of this is the detail of the helicopter rotor blades. They are painted in black with dry brush in silver (Photo 12).

 After which the complete model is painted and aged, apply the decals. They are apply in this point because the film of the decals can stop or turn aside the flow of the washings within the panel lines. In addition, some decals can be damaged by the solvent of the washings; you will have to varnish again after placing the decals. Do not forget to clean any plan of drops of water or setting solution of the decals. Also its recommendable to give another coat of gloss varnish after apply the decals, to seal them in the surface. Apply the last coat with matt or satin varnish, according requires the model. What has good of this technique is its flexibility, the fact is that the obtaining results we had in mind can be changed only with a little turpentine spirit.