Protecting Your Models From Yellowing

I received a great email from Alex today, asking how to keep his models from turning yellow as they age.  "When I first thought of displaying my models I was afraid of yellowing [by the sun]... I am now worried that maybe keeping the models completely out of the sunlight has started the yellowing process."  He asks what the truth is about sunlight and yellowing, and whether he should keep his shades closed to keep the sun off his models.  These are great questions, so with Alex's permission, I'm sharing my answer with you:

Some slight yellowing will nearly always occur, simply because the plastic slightly condenses as it ages, making it begin to appear more opaque (and therefore, slightly yellow or slightly grey), but not much.  Sometimes Breyer will experiment with a finish or paint that ends up reacting with the plastic, and accidentally cause yellowing over time - There's nothing that can be done in that case.  Yours all look really good, though.  Remember, no model is perfect, so love them for their individuality, just as you do your friends.

People online argue back and forth about the value or detriment of sunlight, but in my experience, neither sunlight nor lack of sunlight causes yellowing.  The main causes are smoke from wood-burning stoves, tobacco, and grease/smoke from kitchen stoves.  (You'd be surprised how much of that can get into the air and settle on things.)  My primary recommendation for collectors is to keep their models in a room with the door closed to avoid any accidental smoke or grease yellowing.  Certain wood stains seem to off-gas as well (although I can't prove that), and may react with the plastic for several years after the wood was stained.  

[Breyer models sunbathing on a soft blanket on our front porch.  For information on restoring models by "sunbathing," see my article here.]

Sunlight (the uv rays, specifically) is used to brighten yellowed models and return them to near-new brightness.  That may be where people get the idea that lack of sunlight means yellowed models, because sunlight makes them brighter, but there's no causation there...  It's like saying that lack of soapy water will make your hands dirty, just because soapy water will clean them if they ARE dirty.

As an experiment, I took a very yellowed Project Universe and stood him on a windowsill inside our Low-E windows for over six months without moving him.  The side facing the window was still just as yellowed as the side facing away from it.  I then took him outside to lie on our porch in the sun and he brightened up within a week.  So, if you have Low-E glass windows, you don't have to keep them curtained.  One thing to note is that different plastics react to things differently, and it's possible that the plastic box fronts of boxed models may yellow more quickly if left in the sun, but I'm not positive.

One other caveat about sun through windows, of course, is heat.  Heat can soften the plastic and allow legs to bend under the weight of the model.  Again, Low-E glass drastically reduces the amount of heat that is transmitted through the window, so check, if you can, to see if your home has Low-E glass.  If it does, let the light shine!    If you can't find out, it's best to keep the shade down on any window that faces them.

Above is my Model Horse Room, which is in the loft of our log home.  Can you see what I've done right and wrong about choosing a space for my collection?

The positives:

• They are displayed in open air.  (The china closets on left and right have glass doors, but they hold porcelain, glass and metal models, no plastics.)
• The shelves are double-sided so they're open all the way through, allowing great air circulation.
• The ceiling light is LED, so it emits very little heat toward the horses on the top shelf.
• Our home has Low-E glass windows and skylights, so I can enjoy them in natural light without worrying about fading.

Negatives:

• They are not in a closed room.  In fact, the loft is over the kitchen, so if we burn something on the stove, the smoke and grease rise up into the loft.
• Being on the top floor of our home, they are subject to more heat and humidity than if they were lower.  Because of this, we run an air conditioner in the Horse Room during the summer.

So, the moral of the story is:  Keep your models on display whenever possible, out of direct sun, unless you have Low-E glass.  Store them as little possible, and check them often if they're packed away.  Your models should remain beautiful for a lifetime!

Added 4/3:

Stephanie from Canada sent us this photo to add another aspect to the yellowing discussion.  Below is her set from the America's Wild Mustangs Series from Walmart.  This pair was sold together as a set in 2007.  She bought them new and they have been kept together every day since.  Most of the time they're displayed in the open, but they have also been packed up occasionally.  Look at the difference - One is yellowed while the other isn't!

So, how can we explain this difference in models carefully kept away from smoke by a collector, and always kept together?  This is the perfect example of "sometimes you can't do anything about it."  What I expect happened here has to do with production.  What most people don't realize is that when Breyer produces a mold, they make tens of thousands of them at once, and then just put the whiteware models into their warehouse.  When they need some for a release, they pull them out and paint them.  I suspect that these two were produced at different times, from different batches of plastic, then pulled out of the warehouse to be paired up and painted for this release.  One batch of plastic was either slightly off-white to begin with, or was more susceptible to yellowing than the other.  Variations in the plastic mix, or even the temperature or humidity of the factory on production day could cause these differences.  It sure makes things interesting, eh?