I been collected all the unused decal,problem is that as time pass decal become yellowish, difficult to lift.
is there any solution to this problem?

Hi Richard,

These are very good articles about what you want to know:
Save Those Old or Yellowing Plastic Model Decals

More on Using or Restoring Old Decals

Hi Richard,
I recently had to deal with the same problem with some 44 year old decals. Yellowed decals can usually be fixed by placing them in a sunny window for several days. The UV radiation in the sunlight reacts with the yellowing to turn it back clear. If it is humid at the window you may want to consider placing the decals in a clear plastic bag. It took my decals about a week to clear up. Another poster here stated a few days ago that he put some yellowed decals on his car dash board and they cleared up in a few hours, so I guess it depends on the decals.

My decals had also curled so I flattened them but taping them to a piece of scrap wood. I think this may have been a mistake as most of the decals cracked when lifting them off the paper backing. The cracking may also have been due to my rushing in trying to lift the first couple of decals. Take your time in letting the water soak in to the paper backing before attempting to lift the decal. I also recommend using a decal setting solution to help soften the decals. It's also a good idea to put a clear gloss coat on the model where the decals are to be placed and then seal the decal with another clear coat after they have been set to help reduce silvering.

Just being patient as you work with them will go a long way in making them useable.

Hope this helps.
John

Thanks for the advise.