Please accept my apologies for any typos that you may find in this post. The spell checking routine on the blog software isn't working correctly and it has been difficult to check for all of the errors. They tell us that they are "working on it..."
Since I've been sharing some of my decal projects with you, I thought it might be a good idea for me to discuss my technique and show you my "tools of the trade." This is my typical set-up for decal work and I have everything I need handy, right in front of me.
On the left side of the image, you see a little glass dish that holds the water to soak the decals in. Under the dish is one of those inexpensive candle warmers. This keeps the water in the dish warm as decals get more and more stubborn as the water that they are soaking in cools off. The red & blue bottles are Micro Set and Micro Sol. I can never remember which order to use them so I have a #1 on the Micro Set; it is the wetting solution that keeps the car side wet while I slide the decal into place. Micro Sol is used on the decal after it is properly set to soften the decal film and allow it to form over any irregularities in the car's surface.
The larger bottle with the black lid is Walther's Solvaset. It is similar to Micro Sol but it is much stronger. It really softens the decal film and is only used when the Micro Sol doesn't get the job done.
Scissors are used to simply trim the decal prior to applying it. I have learned that round corners seem to work better than square ones so whenever possible, I round off anything that I'm cutting. The glass is to set the decal on once it has soaked in the warm water but before it is applied to the car. The paper towels simply are used to absorb any excess water. The Q-tips do the same thing but absorb a lot less as you might guess.
Tweezers are used to hold the decal when it is being soaked then moved into position on the car. The smaller decals like to stick to your fingers if you pick them up; especially if your hands are damp. You will notice two paint brushes that I use. One, the black handled one, is just a standard hobby paint brush but the one with the tan/green handle has had its bristles cut way back. This is my stub brush and it can be effectively used to push the decal into final position once it is on the car.
So, when I apply a decal, I first grab the trimmed decal with the tweezers and dip it into the warm water for about 10-15 seconds. Different decal papers react differently so it's important to experiment a little here. Once the fifteen seconds are up, I place the decal still on its backing paper on the piece of glass then touch it very carefully with a corner of the paper towel to take away excess moisture. Once the backing paper has been soaked, you won't need the excess water.
In the meantime, I will apply a generous puddle of Micro Set to the car's side where the decal will be applied. I'll pick up the decal & carrier paper with the tweezers then place it about where I want it to be on the car and then gently slide the decal off of the carrier paper and onto the car using the handle end of the paintbrush. Discard the carrier paper then use the stub brush to gently nudge the decal into place. Once it is where you want it, very carefully touch the edges with either a corner of the paper towel or a Q-tip to blot up the extra water & Micro Set. Continue doing this very carefully and you will see the water leave the car's surface and the decal will set down where you want it to go. If it moves, simply rewet it with some water and move it back into place and start over.
If disaster strikes and the decal curls up on itself, you can sometimes save it by applying several drops of water and try to uncurl it using the paintbrush, the tweezers and any other tool that seems appropriate. Yes, sometimes you lose one and simply can't save it. In that case, you hope you have a spare. When I print my own decals, I always make three sets; one for each side of the car and one so that I have extra pieces in case of a problem.
Once the decal is in place and the excess water is blotted away, allow it to dry for several minutes. Then using the regular paint brush, apply Micro Sol around the edges of the decal. If you watch it, you will notice that it kind of shrivels up like a prune as the Micro Sol does its work. DO NOT TOUCH THE DECAL AT THIS POINT! If you do, you will no doubt end up with one glob of decal film where your lettering used to be and it can't be saved. While the Micro Sol is working, I usually move on to another decal on another car. There's no sense in running the risk of messing this one up while you are trying to apply another decal next to it.
After a couple of hours, I will re-apply the Micro Sol to the decal then carefully press it straight down with a damp cloth. This will help in snuggling the decal down into the scribes and other cast on details of the car's side. No, I can't recall ever ruining a decal at this point in the process. But still I'm careful to go straight down and not move from side to side thus minimizing possible damage to the decal. If after a couple of applications of Micro Sol, the decal refuses to settle down, then I move to the Solvaset using the same basic technique. Once you are satisfied with the results set the car aside and allow your decals to dry thoroughly... at least a couple of days.
There two final steps in the process. First, I get a small damp cloth and gently wash the side of the car. This will remove any excess glue from the decal that may be on the car's side. Once that has completely dried, I will then give the car 3-4 very light coats of a clear spray to seal the decal to the car's side. I kind of like a satin or semi flat clear paint for this step but it is strictly a matter of personal preference. Some modelers like them completely flat; not me.
So there you have it. That is my technique for decal application and tools of the trade. If you have found something that works better, please feel free to share it with the rest of us. Like so many things in model railroading, there may be "better ways" but I'm not sure that there is one "right way."