Painting ABS parts is not recommended due to the risk of damaging them. Modelers who still want to attempt it may use the following painting techniques to help minimize this risk as much as possible.
【 Caution! 】
- These methods are not guaranteed to prevent damage to parts.
- Kotobukiya does not recommend painting ABS parts. Please do so at your own risk.
Why Painting ABS Parts is Not Recommended
When ABS parts are painted, the solvent (thinner) contained in the paint penetrates into the resin of the parts and vaporizes, causing small cracks in the penetrated areas thus making the parts brittle. During and after assembly, load or stress is applied to the surfaces where parts are connected (seams) as well as in movable joints. If these areas have been penetrated by thinner and weakened, they will often break under this load. For these reasons, painting ABS parts is generally not recommended.
Preparation
Important Points During Assembly
Adjust the “fit” between parts
If the “fit” between parts is too tight, it increases the load placed on the parts during assembly, raising the risk of breakage after painting. To lower this load, test fit parts before painting and adjust the fit, by shaving down joints or through other methods.
Disassemble movable parts before painting
Disassemble movable parts before painting and reassemble the painted parts at the end. Joints and other movable areas of kits are designed to be strong enough to operate under load but painting them while they are already under load will increase the risk of damage.
Painting Precautions
Avoid applying large amounts of paint at one time
When a large amount of paint is applied, it takes longer to dry thus making it easier for the solvents to penetrate the parts, as they will be in contact with the solvent for a longer period. Apply lighter coats of paint and allow it to dry before applying more coats to bring out the color.
Do not overthin the paint
Paint is often thinned to make application easier. However, if too much thinner is added, the parts will be directly exposed to the solvent, increasing the risk of damage. If the paint is too thick, it is difficult to apply so carefully thin the paint to the appropriate concentration.
Painting Process
STEP 1: Cleaning the Parts
Soak the parts in water with a few drops of neutral detergent (such as dish soap) for 20 to 30 minutes to remove any oil from their surface. This is done to prevent any oil from preventing paint adhesion and to ensure an attractive finish after painting. After washing, rinse the parts well under running water and allow them to dry thoroughly.
STEP２: Spraying the Base Coat
To help prevent penetration of paint solvents, a base coat (such as commercially available surfacer or primer for models, etc.) is first used to create a protective layer. Spray in small increments, moving the spray can or airbrush quickly from side to side at a distance of about 10 cm (about 4 inches) from the part. Spraying once will not perfectly cover the surface and may leave some mottling, but subsequent coats will take care of this. After spraying one part, move on to the next. After spraying all the parts, start another cycle.
Ideally, the entire part should be evenly covered with gray primer as seen below.
This took three to four coats of paint to achieve.
Base coat spraying completed!
STEP３: Start Painting
From here, we’ll describe the painting procedures separately for hand brushing and using an airbrush (we’re using a standard lacquer paint and the thinner sold specifically for it).
Brush Painting
When applying paint by brush, first work on areas that are difficult to paint, such as corners and concave areas. Use a round, pointed brush with fine bristles. The paint should not be too thin, but if it is too thick it can be difficult to cover everything effectively. Dilute the paint so that it is about the same consistency as new paint.
Next, paint flat surfaces. Use a flat brush and make long, even brushstrokes. It is difficult to get the color to develop fully with one coat so apply two or three coats of paint to finish. Before applying more coats, make sure you allow previous coats to dry completely.
【 Avoid this! 】
In this example, too much overthinned paint was applied in a single coat. In addition to increasing the risk of parts damage, it will take several coats of paint to bring out sufficient color, increasing the time it takes to finish the work.
Airbrushing
Using an airbrush is a great way to finish a model quickly and beautifully. Follow the same rules that were used when applying the base coat.
- Do not apply too much paint at once
- Do not overthin the paint
These are the two crucial points. Take your time when spraying and you’ll be able to achieve a great finish.
【 Bad Examples 】
Two examples of the same part painted differently are shown below. The one on the left was sprayed with too much overthinned paint at once. In addition to increasing the risk of parts damage, it will take several coats of paint to bring out sufficient color, increasing the time it takes to finish the work.
STEP４: Washing
Washing is a popular technique for enhancing the three-dimensional appearance of a model. This is achieved by applying a heavily-thinned enamel-based paint (often gray or black) and letting it flow into the model’s concave areas, such as the panel lines.
However, be careful! Enamel solvents are highly permeable, and if they flow into parts that are under load (seams and joints) or parts that have not been completely painted with a base coat, there is a high risk that the parts will be damaged. Take care to avoid letting the wash flow into these areas.
Appearance after washing.
Precautions
- These methods are not guaranteed to prevent damage to parts.
- We are not responsible for any damage that may occur as a result of attempting these methods.
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