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de-yellowing product for old decals?

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i have recently dusted off some of my late twenties' builds. they're not bad, i guess, but as by then i didn't use -nor i believe there were such products in my country (italy)- clear finishes, the decals, big and small, have become heavly yellowish, and the film supposed to  be transparent, is a yellow-brownish plate around stencils etc.

with the industry always in search of new products for modelers, i wonder if someone could come out with something more realistic than the airy-fairy story of sun exposition :evil-laughter::thatfunny: for decal sheets and /or some specific product for in-place decals in general...

thanks for reading and, in case, giving an answer.

best greetings, bobo.

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The "sun exposition" actually works fine, provided that you leave decals under hot sun light for at least a week...

I did it a couple of times successfully.



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hi phantom riveter.

here on the lago maggiore, italy, we have seldom a whole week of "hot sun light" -they call it sunny italy...

secondly, do you have one pane or two vacuum panes windows? because i have the second type, and this might be one of the reasons why it doesn't work.

finally, i was speaking of old "applied", on model decals that have become yellow 'cause i, at the time, did not use coat finishing. one pays for his sins...

you understand that even having the right sun and the right panes, one cannot sort of "roast" the models so that sunlight can reach every part.

this is why i was wondering of a remedy for decals that yellowed on the model.

thank you for your contribution.

ciao, and happy modeling! bobo. 

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Hi Bobo,


it is the UV content of the sunlight which "bleaches" the decals. So you could use an UV Lamp. The problem is that it will yellow again since the yellowing is the result of the glue ageing and breaking down (the same applies for yellowed vac canopies where the plastic ages and breaks down).



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thank you shorty.

i knew that it is the film  supporting the decal which yellows. in fact, there is no glue involved in the vac-u-formed canopies yellowing.

whatever it be, it seems to be a no way out problem when you say that even once "rejuvenated", decals will yellow again.

it depends in how much time.

also, if you coat with a clear finish the model, it shoud prevent the decal from yellowing again, i suppose.

is it right?

this is particularily important to me as i have some models that i made in my youth when i didn't use the finish coating. 

provided that they wouldn't melt down under an uv lamp, it would be wonderful to restore the decals and then spray the clear finish.

what do you think of this?

thank you in advance.

best greetings. bobo.

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On the canopies, that's the nature of styrene plastic. Perhaps other plastics too. Even an unbuilt 1/72 scale Space Shuttle kit which has been in a box in my closet for, oh, maybe 15 years is having its white plastic yellowing.

On applied decals, it may well be remnants of the adhesive which was used to stick the film to the backing paper. In 1990s Monogram's decals were especially bad about that.

Edited by southwestforests

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