Help Needed - Sealant layer is yellowing

[JackShealander]

I need some advice. I\'ve been to a few painting forums but I have not had a definate answer to whether or not my minis can be saved. I got the advice to use polyurethane sealant from a manager at Games Workshop. I figure that someone else has to be in the same boat as me.

I used polyurethane sealant that was supposed to be colorless and clear to protect my painted Space Wolves. After the polyurethane was applied it was clear and colorless. However after about 4 months of storage the miniatures that I sealed with the sealant has a greenish sheen. The polyurethane coat has yellowed a bit. All the white portions on the miniatures have yellowed and the overall look has a greenish hue because of the yellowish transparent layer over the Space Wolf bule.

I\'m looking for advice on how to reverse the yellowing effect of the sealent. Hopefully someone on this forum has run into this problem and knows a good remedy.

I\'m hoping to find someone who has made the same mistake that I did. Repainting the miniatures is not an option for me. The miniatures were painted by a person far more skilled at it then I will ever be. Is there a way to strip off all or part of the sealant? Or maybe there is a way to paint on another semi-transparent coat to take away the yellowish/greenish look.

Thanks for reading, I\'m starting to get desperate.

 

[finn17]

I share your pain...

You are a bit snookered however.

The polyurethane varnish is the toughest part of the layers applied to the mini. Trying to remove that without disturbing the paint would be a bit like trying to remove a tortoise from it\'s shell...without harming the tortoise!!

You might want to experiment with applying thin coats of an alternative sealer, but I doubt this would work.

Sorry to sound so negative. Perhaps someone else knows something I don\'t?

 

[Frustrated Father]

Jumping on the doom wagon here ... as finn put it so well, sounds like you\'re \'snookered\' (I\'m going to find a way to use that word again somehow today .. heeh).

Don\'t think there is really any way that you can reverse what has gone on already, though adding a matte coat to it \'might\' stop it from continuing.

And not to come off sounding dumb, but is it possible that they\'ve been handled quite a bit of late with \'dirty\' hands? Perhaps a wash is in order? Odds are you\'ve already thought of that.

Sorry to hear about your troubles.

 

[Itchy]

Testors Dull Coat?

Well... a while back i bought a can of what i thought was a matt sealer. But it just said it was matt and was really pretty glossy and even had a slight coloration to it. i JUST found a can of Testor Dull Coat and sprayed it on the mini... completly fixed it. So it might help... it might be a waste of 3 bucks, but i\'d give it a try unless others know the situation better.

 

[aphillipsonuk]

Polyurethane varnish is a plastic product, and can react to sunlight - or more directly Ultraviolet light. In plastic sheet you often see this as the sheet discolouring or becoming brittle and snapping/shattering.

The effect that you described sounds very much like this UV initiated chemical degredation of the sealant.

In varnishes you basically have particles of the plastic suspended in a medium which when dried form literally a thin plastic cover stuck to whatever you sprayed or painted it on. You will NOT get it off without disturbing the paint. (i liked the tortoise and shell analogy!)

The good news is that good quality polyeurathane is usually these days \"UV stabilised\". This means it does not react to sunlight (and other UV light sources). Or more accurately it does - but it takes far far longer exposure to have an effect - often measured in decades!

The bad news is that you cannot reverse this chemical reaction (at least not without putting the varnish back into its solvent state and treating it electrochemically). Likewise anything that you brush onto it is NOT going to reverse the problem. Testors Dullcoat is a great sealant but even it cannot reverse the laws of chemistry.

(Although i admit to never using testors dullcoat as being in the UK its like rocking horse doo-doo over here.)

However a good quality sealant that is UV stable will prevent the situation getting any worse.

Oddly enough covering them in suncream would have a similar effect - factor 10 or more i guess...

Whats intriguing here is that you said after 4 months of storage? how much light have they been subject to? Its possible this is something else, but it sounds very much like UV degredation to me.

 

[JackShealander]

These minis have had very little or no exposure to UV. After spraying the them with sealant, I put them in a army transport case then stored then in my closet.

This means that the sealant reacted chemically to the temperature in my closet (it can get hot in the summers here .. I had them stored for six or seven months now that I think about it) or the paint itself.

I have 10 minis like this. I\'m hoping the yellowing won\'t get worse.

Thanks for the info.