Troublesome Eduard Decals

[DaveO]

Hi everyone, I've suffered a strange problem with decal silvering which has spoiled an otherwise enjoyable build, the Eduard Weekend Mig 21R.

I'm pretty experienced modeller and have never had a problem like this. I may have had a duff set of decals...

After the build I went through my usual process, buffing the paint, airbrushing thin coats of Klear until I had a high gloss, and finally polishing the decal areas. The decals were soaked for 20 second or so, removed and rested on kitchen roll until the decal released. I used Microset and sol and carefully pressed the decals into place and 'rolled' any air bubbles out with a cotton bud.

At first they looked superb and snugged down into the panel lines perfectly.

The next morning, after drying, ALL the decals had silvered, in fact one of the aircraft insignia numbers fell off.

The decals appeared to have no adhesive at all.

Being a Weekend edition I only had the one set of suitable decals. I decided to try my failsafe method to replace them using Klear as an adhesive. All the decals lifted of with a wet paintbrush without damage. The area was swabbed with clean water and they were replaced on a patch of Klear, pressed into place and left over night. AGAIN at first they looked fine, the morning after they had silvered just as badly as the first time.

I've had kits with terrible decals in the past but never anything like this, I was sure the Klear treatment would solve the problem, I'm beginning to wonder if the fault is not just with the printing process (little or no adhesive layer on the paper substrate prior to printing), but with the printing varnish used to create the clear carrier film.

I'm baffled, any suggestions chaps? It looks like this build will end up in file B1N.

[Beardie]

Hmmm an odd one indeed... I had a wee PM conversation with Rowan Broadbent of Pheon and from what he tells me of decal "construction" there seems little explanation for this besides lack of glue. The 'Glue' used is water soluble Gum Arabic so it might be worth getting your hands on some (art suppliers sell it for creating watercolour glazes) make up a thin dilute solution with this and brush the surface of the model with it and then reapply the decals to the surface or if the decals are robust enough dip them in a solution of gum arabic and then apply them. It sounds like there is an absence of this adhesive on the decals. Possibly the solution used in the printing was too dilute or had in some way spoiled. As the decals adhere by the mere "tackiness" of the gum arabic unless the decals are printed with teflon they should still stick.

Is it possible that there is something wrong with your Klear? I never use it myself so can't comment on it.

Edited January 12, 2015 by Beardie

[DaveO]

Hi, thanks for that, I think the decals may have suffered a lot of stress now &may be too well sealed in by now. Good idea about the gum Arabic, many many years ago we used to make decals for flying models by varnishing gummed brown paper tape, painting decals on and then treating them like kit decals... Of course that was in the late Neolithic.

[colin]

Strange, as I have had decals float off into the water before now, I know should keep an eye on them, but still stick to the model and settle down with some micro sol and never come off, even if you wanted to get then off no way.

What were you polishing the decal areas with, could the surface have been contaminated with something during this process, thinking anything silicone based

[Beardie]

I think if the decals are thin enough they stand a good chance of adhering like a vinyl sticker to a windscreen even if the gum has been washed away but I have found that even with Eduard whose decals I have found to be generally pretty good the thickness does vary quite a lot and the thicker the decal the less chance of it hugging the contours without adhesive. According to Rowan the decal inks themselves are acrylic so I can't see them being the problem.

[Beardie]

Just thinking about the Gum arabic side of things it might be worth adding a little to decal water when putting decals on to ensure stickiness. I think I will give this a try on my next kit as I have a bottle of Winsor and Newton gum arabic somewhere. Maybe even a drop of diluted stuff from a dropper on the decal paper after it has been dipped hmmmmm.....

Edited January 12, 2015 by Beardie

[DaveO]

Strange, as I have had decals float off into the water before now, I know should keep an eye on them, but still stick to the model and settle down with some micro sol and never come off, even if you wanted to get then off no way.

What were you polishing the decal areas with, could the surface have been contaminated with something during this process, thinking anything silicone based

Hi there, thanks for your reply - I only polish the area with a dry j-cloth when the Klear has fully hardened, just to make sure there are none of those lump and bums gremiins that appear after a decal has dried. I hope this is a one off - I've a few more Eduard kits in the stash.