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  • Writer's pictureMido

How to Apply Decals

Bringing a kit full of plastic parts to life is about more than just building, painting, and weathering. One of the key ingredients is decals, and that's exactly what we're going to talk about today: why we want them, what they are, how to apply them, and common problems.

Why we want them

Decals are a great way to bring specificity to a model and allows for the practical representation of details that are too difficult to paint. Let me give some examples for the uninitiated:

  • Instrument panels of airplanes and cars

  • Race car body detailing

  • Text markings that would be applied to the real subject using a stencil or a life-size decal

Just think about how long it would taketo say nothing of the accuracyto manually paint all the logos and trim on a 1/24th scale stock race car!

Decal sheet
Sheet of decals from Tamiya's Type 90 Tank w/ Mine Roller

What they are

While there are several types of decals, water slide decal are the ones modelers encounter most frequently. These decals start with a backing paper that is coated with a water soluble adhesive. Then layers of of ink are added to form the image. Lastly, a transparent coating called the carrier film is applied on top. The carrier film is what allows the image to slide off the backing paper and onto your model.

Here is a representative cross-sectional diagram:

How to apply them

For this exposition I will be using some leftover decals from my 0-2 Skymaster build, which you can read about here, and the inside of a tank hull (Tamiya's Type 90 Tank) I have been testing different brush painting techniques on.

Step 1: Add a clear gloss coat, also called a varnish, to your model (Pledge Floor Gloss is commonly used) and allow it to dry for at least 48 hours. A gloss coat will do two important things for you. First it will protect the painted model from the decaling process. Second, it will create a smooth surface for the decals to "bed down" on which reduces "silvering" (more on this in the common problems section). Normally, this will be applied to the entire model, but for this demonstration I will only do a small patch.

Gloss coat
I brush on Pledge Floor Gloss with a wide brush

Step 2: Gather the decal tools such as a tray with water, paper towel, cotton buds, cocktail stirrers, straightedge, hobby knife, tweezers (avoid serrated tweezers if possible), decal solvents (optional).

Decal tools
Common tools for working with decals. You never know what you might need

Step 3: Study the decal instructions carefully. Frequently you will only have one chance to do things right!

Step 4: Cut your decal from the included sheet. Editors tip: now is a great time to replace a dull hobby knife blade or risk tearing a decal. Work slowly and deliberately. A metal straightedge may be useful to guide your knife.

Decal cutting
Take your time cutting out decals and use a straightedge

Step 5: Conduct a "dry test" where you take your cut out decal and place it over the receiving area of the model. At this point, you are looking for any obstacles that might impede proper decal placement. You are also determining the movements your fingers will make and what tools will be useful during placement. Sometimes you might need to cut a decal into several pieces and re-connect them on the model. Decals have a habit of finding their way into difficult places.

Step 6: Place the decal in water for approximately 15-30 seconds. I find that using a shallow vessel with lukewarm water works best. Be careful not to leave the decal in the water too long or else all the adhesive may be dissolved and/or your decal will slide off the backing paper.

Decal in water
Allow the decal to soak for 15-30 seconds

Step 7a: Remove the decal from the water and lay it out on a paper towel. Now is a good time to gently test if the decal is ready to slide off the backing paper. If it isn't be patient for a few more seconds. If it is really being stubborn, a quick dip back in the water should loosen things up.

Decal resting
I like to let the decal rest on a paper towel before placing it on the model

Step 7b (optional): While the decal is sitting on the paper towel it is a good time to add a decal setting solution to the target area on the model. This will help your decal bed down and prevent silvering. Setting solutions come in several strengths and may work slightly different from one to another so be sure to read the instructions on the specific product you are using.

Decal setting solution
A setting solution will help the decal conform to irregular surfaces. I intentionally placed the decal on a creased part of the hull

Step 8: Once the decal is ready to slide off the backing paper it is time to transfer it to the model. Carefully slide it off the backing paper using the movements and tools you envisioned in Step 5. Don't worry about exact placement, you will be able to maneuver the decal around once it is on the surface. If things start to get tacky you can add a few drops of water to keep things moving.

Decal placement
Sometimes a finger works best despite all the tools we have. Be careful not to tear anything

Step 9: When the decal is where you want it to be, take a cotton tip and squeeze any water and air out from under the decal. It is best to roll the cotton tip from the center on out. Editors tip: stubborn bubbles can be popped with a needle.

Cotton tip
Roll the cotton bud from the middle to the outside. You want to push out air and water bubbles

Step 10 (optional): Apply more decal setting solution according to their instructions if needed.

Step 11: Let the decal dry and DON'T TOUCH.

Step 12 (optional): If a decal is not bedding down on the model surface repeat Step 10 and Step 11 as needed.

Decal set
Decal has been set. What's that cloudy residue?

Step 13: After the decal has conformed to the model surface and has dried for at least 24 hours it is time for another gloss coat to seal in and protect all of your hard work!

Decal sealed
Another coat of Pledge will seal the decal and remove the cloudy residue

Common troubles

Silvering - Caused by trapped air under the decal. Cutting away excessive carrier film, using a gloss coat, applying decal setting solution, and rolling out moisture from under the decal will minimize the chance of silvering.

Decal rolled up on itself - Most likely to happen when the decal is being taken out of the water or during the initial transfer to the model surface. Sometimes the addition of strategically placed water drops can help unroll the decal, other times the decal might just be a loss.

Ripped decal - You can salvage the decal by aligning both pieces on the model.

Decal won't adhere - I have read about modelers laying the decal directly into wet Pledge and brushing another layer of Pledge right on top. The idea is to encase the decal with Pledge and allow it to dry.

Cloudiness - See the picture between Step 12 and Step 13. Strong decal setting solutions and adhesives may interact with Pledge. Be patient and let the decal dry thoroughly. Applying another coat of Pledgewhich you will need anyways to seal the decals inshould clear everything up. See the complete photo after Step 13.

Disintegrated decal - You may be able to contact the modeling company and obtain replacement decals, but mostly you will just be out of luck. Unless that is, you want to make a custom decal, the subject of a future post!

Parting thoughts

The novice modeler need not be intimidated by decals if they remember that "slow is smooth, smooth is fast". When I look back at my decal disasters and near misses, they can usually be traced back to cutting corners and a lack of patience for the process: not because something was overly difficult.

This post gives you a starting point for working with decals and in time you will develop your own intuition on "what works best" for you. Like anything, hands-on experience is the key.

Time to let the decals dry!

Thanks for reading,


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