1. Preparing your decal sheet
Decals come in a variety of print types and decal film thicknesses. Some require little preparation, and others require a great deal. Personal skills at applying decals are also a factor to consider. This guide will assume you have a beginner's level of ability, but will also include some tips for more experienced modelers. It will also focus more on using Acreation Models decal products.
The first step any modeler should consider is how to prep your decal sheet for use. Acreation Models decal film is thinner than most decals included in kits. This means they are more likely to tear or fold on you if you are not careful. Some of us have clumsier hands than others, including myself. I always prepare my decal sheets for use by applying an additional coat of Testors Decal Bonder Spray. This gives the decals an additional layer of film which provides more rigidity to the decal. The additional thickness gives the decal more strength and makes it less likely to tear or fold on you.
When applying Testors Decal Bonder spray, you want to make sure the temperature is lower than 90 degrees Fahrenheit. Humidity in the location you spray will also cause the drying time for the spray to be different. The higher the humidity, the longer it will take the spray to dry. The sheet should be vertical against a box or spray booth. You want to start spraying off the paper, and move the can left to right and right to left as you work from the top of the page down. You want to move the can quickly and with the spray nozzle 12-18 inches from your sheet of decals. You want a very light coat of the spray. It should be an even coat, and you should overlap your spray by an inch, approximately. You should NOT have it so thick it runs or forms pools.
As soon as you have finished applying a single coat, you should immediately lay it flat. You may choose to cover it with a box to minimize dust landing on the wet spray. It will dry to touch in 5-10 minutes, and be ready to use in an hour. You may want to apply multiple coats to build up some thickness if you still have difficulty with the decals, in which case you want to apply your second coat after the 5-10 minutes have dried it to touch but before it has cured. Add an additional 30 minutes to the drying time for each additional coat of spray. Three coats should have a 2 hour drying and curing time. Again, in a humid environment you might want to let it dry overnight. If you have pets, put the sheets up where they will not walk on them.
2. Preparing your model's surface
Before applying decals, complete any painting work you have to do. Exceptions to this could be weathering, which has been addressed in the 7th section of this guide: Finishing your model. Acreation Models decals are semi-transparent and can be applied over weathering, or have weathering applied later. For dark washes, I recommend applying the wash before you apply decals so that the wash does not accumulate against the thin edges of the decal film. Murphy's Law is merciless, and 9 times out of 10 it will make those edges visible.
When you've applied any painting and washes you want, and it has all dried and cured *(make sure you follow the instructions for whatever paint you are using, and follow their dry and cure times), you should apply a coat of Clear Gloss finish. This step provides a layer of protection and also builds an ideal surface for your decals. Silvering of decals occurs when there are microscopic pits in the paint surface, creating microscopic air bubbles underneath the decal. 2 or 3 light coats of Clear Gloss finish will provide a smooth surface without pits so that the decal gets a nice smooth surface to adhere onto. Try to apply the Clear Gloss coat to the entire model, so that you end up with a uniform finish at the end. Occasionally you may choose to isolate sections of the model and spray the Clear Gloss only where the decals will be. It is up to you to determine the best method for your model. A Flat Clear coat will not provide a good working surface for the decals, and should not be used for this layer.
3. Working efficiently
One problem I often encounter is getting my decal sheet wet before I am ready for it. To fix this I have since developed a strategy for working which has helped me work better. I have a wet surface and a dry surface area on my work table. I am right handed, so my dry area is on my right hand side, the model in the middle, and the wet area on the left.
On the dry side I use a self-healing cutting mat with a fresh x-acto knife blade. I will cut decals out of the sheet, cutting as close to the edge of the artwork as I can without cutting into it. I will cut out several sections and leave them in the dry zone until I am ready for them. I also keep a small hand towel nearby to dry my hands before cutting more sections out to use.
On the wet zone, I keep my tweezers and brushes and a bowl of lukewarm or room temperature distilled water. Any wet paper backing from decals that have already been applied accumulates here and I keep them toward the edge so that they do not stick to my hand which may then go to the dry area and accidentally ruin a portion of your decal sheet.
When applying wallpaper decals such as Aztec decals, it is best to work in sections. Also important is to consider where you will be holding the model and where it might rest on the table while you are working on it. You do not want to apply models to the areas where it will contact your work surface, and possibly push the decal out of position or remove it from the surface altogether. For Star Trek models, I find it best to leave off the bridge, nacelle tops and engineering hull bottom decals until last so that the model can rest on these surfaces until you're finishing the rest of the decals.
4. Applying decals to your model
Tweezers help hold the sliced decal section in the water so you aren't constantly getting your fingers wet, which may damage your unused decals. I hold the section under the water, and shift the position of the tweezers so that the paper backing under the tweezers gets some water too. I hold the section under the water until I see the backing paper soak through to the front side with the artwork. It usually takes about 10-15 seconds to soak through. The larger the section, the longer it will take. I will then remove it from the water and tap off any excess beads of water hanging onto the decal.
I hold it in the tweezers for another 20-30 seconds to let the water activate the water soluble glue that keeps the decal on the paper, and later holds the decal onto the model. I gently nudge the decal with a wet paintbrush. If it is ready, it will slide easily. Do not try to force it to move, as you will likely cause it to tear. If it doesn't move with gentle pressure on the paintbrush, give it more time to work. If it doesn't seem to be sliding easily, dip it in the water again for a few more seconds.
Before applying the decal I like to dab my brush in the water and brush a little water onto the surface of the model where the decal will be going. A little water goes a long way, and you do not need to flood the surface. Also before I apply the decal, I consider the shape of the section, and if it has any peninsulas or other awkward cuts which might make placement more difficult. You want to keep peninsulas on the backer page until they slide into position. See figures # and #. Slide the decal a small amount, just a couple of millimeters off the paper in the direction you want it to slide, and grip the exposed paper with the tweezers so that the decal can still slide freely. Hold the decal over the section it goes on, and touch the overhanging section to the surface, and stick it down with the brush tip. Using the brush to hold the decal down to the model, slide the paper backer free and let the decal settle into its place. If you need to adjust it gently nudge it with the brush until it's in the final position where you want it to be.
Some people prefer to use a setting solution such as Microscale's Microset. If you use a setting solution use a different brush for it and do not mix it with your water bowl. Mixing the setting solution into the clean distilled water may cause damage to the decals that won't appear until much later after you've finished the model. Do not use Solvaset on Acreation Models decals, it is too hot and may damage the decals.
5. Sealing your decals
Once you've applied all the decals you're going to do in a session, allow the decal to dry completely. You should give them at least 8 hours to dry, and most people prefer to let them dry overnight. Do not touch them while they dry.
After they have dried, you may need to use a solvent such as Microscale's Microsol to soften the decals and settle them into the surface of the model. This could be a valley in the surface, or where the decal bends over a mountain, or over a scribe line. Again, do not mix water and Microsol. Dip your brush in the bottle of Microsol and gently paint the solvent onto the decal surface. Do not soak the decal with a flood of it, instead slowly paint it on in small amounts and let it dry. It may take 2 or 3 coats to get a decal to settle fully into a large crack or valley. If you require this step, then allow the solution to dry for at least 8 hours or overnight.
Once your decals are applied and dried, including drying after any solvent, apply another coat of Clear Gloss to seal the decal section to the model. This will prevent future handling from damaging the decals you've already placed. Again, this layer must be a Clear Gloss finish, not a Flat Clear coat. Flat Clear finishes etch the surface they are sprayed on creating microscopic pits. This is what gives it the flat appearance and it will damage the decal film and the artwork printed on them. See section 7 for using Flat Clear coats.
You may not finish the entire decal placements in one sitting. If you have to wait a few days or longer to place more, you should apply a Clear Gloss coat over the work you have finished so that it is not damaged while you are not working on it.
6. Applying multiple layers of decals
Some models may require multiple layers of decals. Star Trek models, for instance, may have a layer of Aztec wallpaper decals, underneath registry decals and other markings such as the Starfleet pennants. After applying the first layer of decals, most likely the Aztec decals, you should seal the layer with a coat or two of Clear Gloss. Again, do not use Flat Clear for this step. Allow the Clear Gloss coat to cure, which may take 12 hours or 3 days. Follow the drying times instructed by your paint. Once the Clear Gloss has dried and cured, you may place the next layer of decals using the same methods as described above. Each layer of decals should be applied onto a gloss finish, and should have a clear gloss layer above them to seal them in and protect them.
7. Finishing your model
Now that you have finished applying all your decals, and sealed them to the model with a coat of Clear Gloss, you can apply a coat of Flat Clear to eliminate the shine of the gloss coats. This will unify all the sections and make the decals appear to be painted on.
Ideally, decals should be applied after all your paint work has been completed, however there may be occasions when you need to do some painting after decals are applied. This may be weathering which should be the last layer of paint. Apply weathering on top of the clear coats which cover the decals, after all, the model you are building would have had its markings painted on before it was weathered.
8. Additional Tips
If your decals are older, sitting in a shelf, drawer, or wherever for a couple years, apply a fresh coat of Testors Decal Bonder Spray or Microscale Liquid Decal Film to eliminate any microscopic cracks in the surface which may cause the decals to break up when you immerse them in water.
You may choose to wear latex or nitrile gloves while applying decals to minimize your skin's oils from contaminating the decals or the model surface. If you are using your hands to hold your model while placing decals, use gloves.