Decals, Shelf Life, and Other Issues.

[2002p51]

I recently had an issue with a couple of aftermarket decal sheets that I've had for years and just recently wanted to use. First let me say that I store my decals the way they always tell you is the right way. They are kept in the original packaging, inside sleeves, in a loose leaf binder, in my work room which is inside the house. So it's not humid, not too hot, not too cold, etc. etc. 

It's possible that the sheets in question (and I'm not going to mention any brand names) were around 20 years old, always stored as described above. When I tried to use them just recently they proved to be very brittle and, upon application, they cracked in several places, and broke into several fragments, and they were impossible to salvage. 

The other issue I've noticed is yellowing after application.

I built this car and photographed it in February of 2014.

 

 

These are aftermarket decals that were more than 20 years old, again, stored as described above. There were no problems with these, they went on easily and looked good.

Less than two years later, they look like this:

 

This model is not subject to direct sunlight or extreme temperatures or anything like that, and still these old decals are yellowing pretty badly. 

So, I'm not looking for a solution from any one, just wondering if any of you are experiencing these or any other problems with long term storage of aftermarket decals?

You may want to check your stock and/or re-evaluate your storage methods.

[louie]

I apologize for not being able to answer any of your questions, but after reading what you are asking and looking at the before and after pictures I would very much like to know if anyone has any answers to these issues. I don't believe that I have had a problem with the decals yellowing  ( after being applied to the car ) . I have had the issues with the brittle, falling apart when trying to apply problem. My issues have not been with aftermarket decals but with the 30 plus years decals which is totally understandable but isn't there something that can be done to preserve or prevent this from happening. I believe now that I am thinking about it, isn't there a solution out there for decals called  ( micro sol ) or something like that. I only have read about it somewhere a very long time ago . Sorry for jumping into your post I am just curious about any answers to these questions of yours.  Thanks.      Jeff 

[2002p51]

Feel free to jump in Louie, I had no questions and wasn't looking for answers, specifically, just wanting to start a discussion.

[gtx6970]

I've had some issues with Slixx decals sheets splitting apart when trying to remove them from the water / apply them. But as far as I know I havent had any yellowing issues with any decals  once applied . Be them kit decals , slixx or Fred cady. And I have at least one build with fred cady decals thats well over 20 years old now

[bbowser]

I've had similar issues of yellowing on some NASCAR builds, both manufacturer and aftermarket, after a few years.  I used MicroSol on them to get them to conform and wonder if that wasn't the culprit?

[louie]

Feel free to jump in Louie, I had no questions and wasn't looking for answers, specifically, just wanting to start a discussion.

oh,okay . Well you definitely got me into the discussion and thank you. My main concern with decals is the age factor of some. I have only used a few decals that where 20 years plus and did have a couple of them just crumble when used. Is there anything that can be done to prevent this or at least minimize the  ( falling apart ) issues. Any suggestions would be greatly appreciated. Thanks.    Jeff 

[High octane]

oh,okay . Well you definitely got me into the discussion and thank you. My main concern with decals is the age factor of some. I have only used a few decals that where 20 years plus and did have a couple of them just crumble when used. Is there anything that can be done to prevent this or at least minimize the  ( falling apart ) issues. Any suggestions would be greatly appreciated. Thanks.    Jeff 

Spraying the decal sheet with a couple of light coats of clear lacquer, and letting them dry for 24 hours or more before using them might help the problem of decals splitting, cracking, and crumbling when soaking them in water. At least that's what I would do.

[SfanGoch]

I have a giant collection of 40+ year old Microscale decal sheets, 30 y.o. Super Scale sheets and piles of old car kit sheets. I store all of them in gallon-sized Zip-Lock bags. Aside from a couple few decal sets for assorted Hawk kits, I haven't experienced any yellowing or other physical deterioration. One method to get rid of the yellowing is to tape the affected decal sheet onto a window which faces sunlight. Leave it exposed to the sunlight for a couple of days and the yellowing will be bleached away by UV radiation. It only affects the clear parts of the film and the solid colors remain, well, remain colorfully solid. This was something I picked up years ago in a hobby mag and, strange as it seems, it works.  Like Nick suggested, spray some light coats of clear coat (Krylon Clear Acrylic works well) or get some Microscale Liquid Decal Film. It brushes on and preserves old decals. Using either will require you to cut the decals off and trim the excess film around each individually, though. Small price to pay if you really need them.

[louie]

Spraying the decal sheet with a couple of light coats of clear lacquer, and letting them dry for 24 hours or more before using them might help the problem of decals splitting, cracking, and crumbling when soaking them in water. At least that's what I would do.

thanks ,that's a really good idea. I have a project coming up that I was considering using some older decals but I think I will give them a try using your suggestion. Thanks High octane, I do appreciate it.        Jeff 

[2002p51]

One method to get rid of the yellowing is to tape the affected decal sheet onto a window which faces sunlight. Leave it exposed to the sunlight for a couple of days and the yellowing will be bleached away by UV radiation. It only affects the clear parts of the film and the solid colors remain, well, remain colorfully solid. This was something I picked up years ago in a hobby mag and, strange as it seems, it works.

This is, indeed, a very old trick that's been around for a long time. Wouldn't have helped in the case of the Ford I posted above however. Those decals looked fine on the sheet and didn't start to yellow until more than a year on the model. It seems very strange to me.

[SfanGoch]

Another method is to scan and print a copy of the older decals onto a new sheet of clear decal paper, just in case. If the decals don't contain white in the design, you're good to go. Otherwise, you'll have clear carrier film where the white would normally be. That wouldn't be a problem if the surface to which it's to be applied is white, though.

[louie]

I have a giant collection of 40+ year old Microscale decal sheets, 30 y.o. Super Scale sheets and piles of old car kit sheets. I store all of them in gallon-sized Zip-Lock bags. Aside from a couple few decal sets for assorted Hawk kits, I haven't experienced any yellowing or other physical deterioration. One method to get rid of the yellowing is to tape the affected decal sheet onto a window which faces sunlight. Leave it exposed to the sunlight for a couple of days and the yellowing will be bleached away by UV radiation. It only affects the clear parts of the film and the solid colors remain, well, remain colorfully solid. This was something I picked up years ago in a hobby mag and, strange as it seems, it works.  Like Nick suggested, spray some light coats of clear coat (Krylon Clear Acrylic works well) or get some Microscale Liquid Decal Film. It brushes on and preserves old decals. Using either will require you to cut the decals off and trim the excess film around each individually, though. Small price to pay if you really need them.

I Thank you for this advice too. Would 1 heavy coat work or 1 light coat or a multiple coats of clear work?  If you it does not matter than I will just use my best judgment. I appreciate your help with what you have said in your above post. I am always thankful to any and all help. 

Jeff

[SfanGoch]

A light coat or two sprayed on is sufficient to cover, seal and prevent the older decals from disintegrating. You don't want to apply a heavy coat of either clear acrylic spray or Microscale Decal Film. You'll only end up with thick decals which would be noticeable after application onto the model surface.

 

[Harry P.]

Since the decals in question looked fine when originally applied to the model, but only yellowed after, my guess is the glue used in their manufacture (the adhesive layer between the backing sheet and the decal film itself) is of pretty poor quality or has impurities in it, and once activated by water, a slow chemical breakdown began. Too bad, because there's not a whole lot you can do now to fix them. Maybe a dose of direct sun would help, but that would also tend to fade the colored areas, too.

[Tom Geiger]

A question for those who have had decals yellow on their models...   do you smoke?  Especially in the room where your models are displayed?  I remember someone having a problem with model chrome yellowing and that was the culprit.

[Harry P.]

I think smoking would have yellowed the entire model, not just the decals.

[SfanGoch]

It sure would. The yellowing is caused by the glue ageing and breaking down. If you examine old decals, it only occurs underneath the decals themselves, not the surrounding paper. The water activated glue is similar to what was once used on lick n' stick postage stamps. My late Dad was an avid philatelist and he had old mint sheets where the glue side was yellowed from age and cracked from shrinkage. This would also cause the decal carrier film to become brittle and break up. This is why I suggested printing a copy on fresh decal paper as an alternative. Yeah, intellectual property, copyright, yadda, yadda, yadda.....we all know things like this are done all the time. As long as what you're reproducing has been unavailable for an extremely long time and it's for your own personal consumption, I don't see the harm in it. Resin guys have been doing it for years. 

[Art Anderson]

Since the decals in question looked fine when originally applied to the model, but only yellowed after, my guess is the glue used in their manufacture (the adhesive layer between the backing sheet and the decal film itself) is of pretty poor quality or has impurities in it, and once activated by water, a slow chemical breakdown began. Too bad, because there's not a whole lot you can do now to fix them. Maybe a dose of direct sun would help, but that would also tend to fade the colored areas, too.

For years (and pretty much still the same) decal film has been made by applying a clear lacquer film onto blotting paper that has been coated with a thin layer of ordinary gelatin, which is the "glue" used, as it's water-soluble.  Gelatin, being an animal byproduct, is naturally lightly yellow in tint (you can find pure, unflavored, un-tinted gelatin in your supermarket, BTW), so if there is a lot of gelatin adhesive underneath a decal, it will eventually yellow even more.  It's a natural thing, not due to any "breaking down" or contamination, from what I have been told.

Art

[Art Anderson]

I think smoking would have yellowed the entire model, not just the decals.

Tobacco smoke (and for that matter, fumes from cooking) will "yellow" things, such as models, but almost always that tends to be on upper surfaces, as the particulates in the smoke or cooking vapors settles by gravity.

Art

[Harry P.]

For years (and pretty much still the same) decal film has been made by applying a clear lacquer film onto blotting paper that has been coated with a thin layer of ordinary gelatin, which is the "glue" used, as it's water-soluble.  Gelatin, being an animal byproduct, is naturally lightly yellow in tint (you can find pure, unflavored, un-tinted gelatin in your supermarket, BTW), so if there is a lot of gelatin adhesive underneath a decal, it will eventually yellow even more.  It's a natural thing, not due to any "breaking down" or contamination, from what I have been told.

Art

Then why don't all decals yellow?

[935k3]

I also have heard that acid in the backing paper causes this. If you ever had any older Cartograf decals they are on a blue tinted paper and they never seem to yellow. I have some that are almost 30 yrs old that have not yellowed.

[Yenkocamaro]

While I've never experienced this, I've seen plenty of original old 50's-60's kits built back then, that were decaled over the bare plastic, and had this yellowing going on. Just a suggestion, but perhaps a coat or 2 of clear, after decal placement, would keep this from happening. Just remember to allow ample time for the decals to dry and set. Decals can be negatively affected by too heavy of a first coat of clear, so a light first coat, is recommended.

Happy Holidays!

Cheers,

Lance

[SfanGoch]

Then why don't all decals yellow?

All decals aren't created equally, or something to that effect.  I dug through my decals and ran across a Scale-Master set which was included with the 1980'ish Hasegawa 1142 S-3A Viking. The entire sheet, including the portions sans carrier film, was yellowed. I decided to run an unscientific test. I cut out identical tail codes with plenty o'yellowed clear film visible. Both were soaked in lukewarm water. The first one was applied to a piece of plain white styrene  without any other preparation. The second was applied to another piece of styrene that was surface prepped with some Microscale Micro Set. After both were allowed to dry, the first decal still had a noticeable yellow tint under and around the decal. The second, prepped with Micro Set, was crystal clear where it was supposed to be. The Micro Set removed the discoloration completely. I also tested this out with ancient discolored decals from an original 1962-issue Hawk Lockheed U-2 with the same results. The results should be identical with the decals Drew used.

 

 

Edited December 21, 2015 by SfanGoch

[peteski]

It sure would. The yellowing is caused by the glue ageing and breaking down. If you examine old decals, it only occurs underneath the decals themselves, not the surrounding paper. The water activated glue is similar to what was once used on lick n' stick postage stamps.

But that water-soluble glue you mentioned is evenly applied to the entire decal paper sheet (not just under the film of each decal image).  IMO, it is the clear film itself that yellows (not the adhesive).  Or maybe the adhesive reacts with the clear decal film causing yellowing?

Like you, I had success bleaching the unused yellowed decals using sunlight. I have not tried UV-bleaching the ones applied to models.

[Art Anderson]

Then why don't all decals yellow?

Could  well be the grade of gelatin, or else some other water-soluble material,  In addition, there are non-yellowing clear lacquers out there, synthetic in their formula.  Earlier lacquers were a natural base, very similar to common shellac, which does yellow with age.

Art