Many of us deal with older kits and the attendant yellowing of the lacquer clearcoat on the decals. Over time the clear becomes a grizzled yellow that is promininet on all but the darkest of backgrounds. Home brew decals are a pain since the yellow invariably is picked up in the scan, and the underlying detail may become lost.

In reading through some of the scale model forums (FSM and hyperscale) there is a technique to bleach the clearcoat back to reasonable clarity prior to application. It is very simply solar bleaching. The decals are placed into a dry bag (zip loc seems to be the preferred) in as low a humidity environment as possible. This bag is then placed in a prominent southern facing window. Dependent upon your latitude and the time of year, the bleaching can occur in days to weeks - but care needs to be exercised since the difference between a bleached clear coat and bleached colour is extremely fine. The absecnce of humidity is an imperative or the adhesive may be activated while in the bag. Also you would not want to overlap sheets or stack them.

I am not suggesting that we should stop pursuing after market decals or replacements. There are far too many quality vendors that have really good product. But when all other possibilities are exhausted this may work to provide you with the markings you need.

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SAM 002
NAR 91005
"The complexity of living is eminently favored to the simplicity of not."

I've heard of the sun-bleaching method from others as well for decals. I didn't hear anything about putting them in plastic bags though.

To keep the humidity down you could put one of those tasty silica gel packs in the bag.

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Scott D. Hansen
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WOOSH NAR Section #558

I think that the bag is to protect the naked decal from any condensation that may accumulate on the glass.

__________________
Gravity is a harsh mistress
SAM 002
NAR 91005
"The complexity of living is eminently favored to the simplicity of not."

It works quite well. I've cleared up decals several times by taping them in the window.

I have never used a plastic bag, but I have double pane windows and haven't needed to go that route. It shouldn't be a problem in the summer anyway, as condensation will be on the outside of the window.

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I love sanding.

I think there are at least three variables that come into play in terms of how long this takes. The level of discoloration in the lacquer, the duration of sunlight your window receives during the day, and the relative intensity of the sunlight. I read everything from three weeks in Vermont to a couple of days in Jacksonville.

__________________
Gravity is a harsh mistress
SAM 002
NAR 91005
"The complexity of living is eminently favored to the simplicity of not."

Living in the northern half of a duplex, I have no southern facing windows - so I just tell people that "yellowed" is my color scheme

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Dale Greene

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Bill

Don't go by any formula or anybody's set recommendation on length of time. Just check it each day until the yellowing is gone. That will cover all three variables.

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I love sanding.