Theory behind pink highlighter marks

[Foxtale]

Here is one more thing to add to the mix.... when talking about G3 ponies. I purchased a few different Styling Sized ponies (Rarity, Rainbow Dash and Cherliee) and they all have "highlighter" pink marks which I know for a FACT are from the stickers that came with them to "decorate" them. Some had the marks in the shapes of the stars and necklaces, while others I had to peel off those nasty stickers to clean and it was pink under. Those stickers were white so it was the type of glue used, not the color/dye of the sticker.

As others have said, I believe the Pink Highlighter is a result of a foreign substance with prolonged exposure to the pony leaving a mark (except for in the case of re-grind).  Stickers (like price stickers or just kids with stickers) and "Makeup" are huge factors (think Pretty Ups and Pony Makeup).Mostly things of an oil type base like plastics (so other pony plastics like saddles are included). In the past, I have found pink marks developing from touching certain plastic bags over an extended period of time regardless of the bag color.

Pink I think just happens to be the color that this type of vinyl turns when exposed to these other substances for extended periods of time. I have had other PVC toys turn GREEN instead with the same thing. 

These are all just theories of mine though based on observation

[Haruna]

I am pretty sure its just a type of plastic break down - especially when plastic is breaking down due to water exposure of some kind. Its the reason you often see pinkish shades around plug holes or the base of taps. Often highlighter does not fade out which points often to it not being a stain - from hair or clothing. Also it pops up in the weirdest places on ponies - places where neither clothing or hair actually reaches and on ponies which have completely different hair colours.

It's certainly possible that it could be regrind -- I see what you mean about the strange places it turns up, and regrind certainly does that. It's just weird to me that the white ponies I'm working with (Big Top, Moondancer) would have their white plastic turning to pink, and only in one or two spots (on their faces, coincidentally). Not like regrind, you know? where often the pony's whole body will be taken over. It could be, but I still think it's the hair . . .

And yeah, I totally agree that stickers, pony bridles, and such can change a pony's color. A Locket that came in Big Top's lot has an unfortunate orange price-sticker-shaped orangeish circle on her shoulder. Thankfully her hair hides it and she's still pretty otherwise. And I have a stylin' size Rarity with bright pink marks left on her after I removed the stickers a little girl had put on her. I'm just thinking of the smaller, randomly-placed bright pink marks you'll find where it doesn't make sense that a bridle or saddle or something was there.

The fading pink hair would surely leave hair stains on their original ponies too, but it doesn't.  Like Surprise gets around her hair no matter condition. 

I totally get where you're coming from --Surprise's hair definitely leaches onto her body around her hair -- but I think the fading pink ponies can get that stain around their hair like Surprise does, too, you know? My Yum Yum, for instance, has pink stain leeched into the plastic around the base of her mane and around her tail. (That's what you meant, right? )

I've seen the neon yellow in the 2nd-release rainbow ponies bleed onto the pony. But it's a very strong pigment to begin with.   If the hair has enough pink pigment, it's possible to see some transfer. My promqueen sister Sweet Sundrop has some pink marks from her hair under her mane and her tail.  But it's faint, and not bright like the typical highlighter type marks.

Yeah -- I'm thinking that the pink pigment has to be both strong and prolonged to get the bright marks. Fading-pink-haired ponies often get that pink color directly around where their manes and tails are rooted, right? But not usually on their bodies (with the exception of my Yum Yum and your Sweet Sundrop), though their hair has frequent contact with their bodies. I think that's because, where they're rooted, their manes and tails have had prolonged, 20 or 30 year contact with that pink pigment. (Same with Surprise, etc., coincidentally.) I think the pink hair has to be pressed up against the affected surface (i.e., the pony) for a prolonged period of time, as can often happen when ponies are stored together. I know from the Ebay seller that Big Top's lot was her childhood collection, and Moondancer's lot looked like a childhood collection (correct accessories included with the ponies and everything), so I think they were stored for some time.

So that's my two cents so far . . . keep the comments coming; maybe we'll get to the bottom of the highlighter mystery.

[NoDivision]

Hm, I have to say I've never really seen pink around the hairlines of fading pink ponies, at least I've not noticed it on any of mine - not a dark bright pink at any rate. You'd think if that were a contender for causing all of these 'mystery' marks then it would be much much more widely seen. However, assuming it does stain sometimes, I just don't think that hair color would make stains as dark as the typical highlighter marks that I see. It's just not a color match. Doesn't really seam feasible to me.

[SeashellnBubbles]

I mean ponies in addition to Party Time, Galaxy and the rest of the regrind gang Although it is possible its a similar concept as regrind to be honest. Manufacture uses base pellets in a variety of basic colours in order to get the right shade - almost every shade includes some percentage of each colour so all of the pink highligher marks could even be a result of regrind/jazz.

I love this answer! "Wedunno what it is...it's just JAZZ!"
I think perhaps the pink staining is random because the ingredients in each pony's plastic is specific to that lot of ponies. The ingredients could age/react to various exposure to various things...and plastic has those different ingredients due to cost. Many times you'll see in a box of cereal or other item "may contain traces of..." Or "contains corn or wheat or rice" or whatever variable. That's because the manufacturer is using whatever is cheapest on the market at the time, and instead of the more expensive cost of changing the packaging with each change, they just list it like that. Those are edible objects, so they have to be specific, whereas with plastics and such, the ingredients don't need to be listed anywhere. The ponies may also have varient in the amount of flame retardant, or other additives depending on what is required by law, like paint having lead in it.
Phenols are an ingredient in some plastics (especially older plastics) and it changes to a pink color when oxidized for long enough. Personally, after doing some research, i think perhaps it's these phenols that are turning the ponies pink, which it why it's ALAWAYS pink and never, say, blue or purple!

[MiRaja]

The fading pink hair would surely leave hair stains on their original ponies too, but it doesn't.  Like Surprise gets around her hair no matter condition. 

I totally get where you're coming from --Surprise's hair definitely leaches onto her body around her hair -- but I think the fading pink ponies can get that stain around their hair like Surprise does, too, you know? My Yum Yum, for instance, has pink stain leeched into the plastic around the base of her mane and around her tail. (That's what you meant, right? )

Are you sure she hasn't be repinked?   Now, that certainly will cause the hair to leech out on the bodies.  These dyes people use to repink or change the color of the hair are not very fast, no matter what claims are made, and that certainly *can* cause staining.  I have quite a few ponies in my collection who still have very pink hair, despite having fading pink, and do not have any leach in their hair. 

I do believe the bright red hair could cause some staining, like what is used on Sugarberry and Paradise.  A lot of times RED will stain as PINK.  I've seen it from My Little Pony to Kimono. 

I just don't buy the theory of kids with highlighters for the stains.  Most highlighters would be sold in sets of different colors and stains are predominately pink.  Strangely enough, most of these pink stains match the same color stains when you get really bad 'saddle sores,' so I think predominately, these stains are from plastic accessories. 

Then followed by red hair.

Then followed by Regrind, depending on the pony. 

It's a lot of different causes, to be honest, but I do believe the main culprit is plastic transfer. 

[hathorcat]

I mean ponies in addition to Party Time, Galaxy and the rest of the regrind gang Although it is possible its a similar concept as regrind to be honest. Manufacture uses base pellets in a variety of basic colours in order to get the right shade - almost every shade includes some percentage of each colour so all of the pink highligher marks could even be a result of regrind/jazz.

I love this answer! "Wedunno what it is...it's just JAZZ!"
I think perhaps the pink staining is random because the ingredients in each pony's plastic is specific to that lot of ponies. The ingredients could age/react to various exposure to various things...and plastic has those different ingredients due to cost. Many times you'll see in a box of cereal or other item "may contain traces of..." Or "contains corn or wheat or rice" or whatever variable. That's because the manufacturer is using whatever is cheapest on the market at the time, and instead of the more expensive cost of changing the packaging with each change, they just list it like that. Those are edible objects, so they have to be specific, whereas with plastics and such, the ingredients don't need to be listed anywhere. The ponies may also have varient in the amount of flame retardant, or other additives depending on what is required by law, like paint having lead in it.
Phenols are an ingredient in some plastics (especially older plastics) and it changes to a pink color when oxidized for long enough. Personally, after doing some research, i think perhaps it's these phenols that are turning the ponies pink, which it why it's ALAWAYS pink and never, say, blue or purple!

ROFL - unfortunately I actually meant it literally. Jazz is a real thing - its what you call coloured plastic pellets which are the product of recycled plastics.

[Foxtale]

Phenols are an ingredient in some plastics (especially older plastics) and it changes to a pink color when oxidized for long enough. Personally, after doing some research, i think perhaps it's these phenols that are turning the ponies pink, which it why it's ALAWAYS pink and never, say, blue or purple!

Yep, I completely agree. I think the process is initiated sometimes by the ponies coming in contact with another substance.