On the show, why does Daenerys Targaryen have dark eyebrows? Isn't her platinum/gold/silvery hair supposed to be her hair all over? ... this couldn't possibly by an effects gaffe that the showrunners argued with Emilia Clark about - could it?
Blondes can naturally have dark eye brows
As already mentioned, Blondes can have naturally dark eye brows, many do in fact.
Actress' natural appearance
The actress is originally a brunette and therefore it is understandable that she might not want to get her eyebrows dyed for years. She wears a wig to pull off the silvery outlook and that's about it.
The lighting in the shooting can make light eye brows almost invisible. A prime example here would be Helga from Vikings, whose eyebrows look bad to be honest. That is of course, if you can spot them at all. And bear in mind, those are her real eyebrows.
Legal and medical issues
Coloring eye brows is medically dangerous and in some places, illegal.
There are no oxidative dyes that are approved by the American FDA for use on eyebrows due, in large part, to the high amount of ammonia used in the color. Concentrated ammonia can cause nerve damage. Bear in mind, just under your skin, hidden behind your eyebrow a mere millimeter or so, there is a major facial nerve.
So usage of such dyes would be technically illegal although I am aware that many hair saloons in USA offer such services nevertheless.
This can lead to blindness or facial paralysis, a fate producers might want to save their lead actress from. Not to mention, to save themselves from lawsuits.
Why don't they use alternatives?
As you suggest, painting is a viable alternative (Although I don't quite see how they could paint the dark hair blonde without bleaching it first but then again I am not a hair styling expert so lets assume it is a safe alternative). Moreover, eyebrow wigs are also available.
So why don't they use the alternate methods? No Idea. There's nothing on the internet which suggests why they did what they did. A safe guess would be that the actress isn't open to those methods at all.
What say you, Oh Martin?
Official response of GRRM, author and creator of the series, on this issue is:
That again? Really?
As you can see, they aren't very bothered about the minor details. The fact that blondes can have darker eye brows makes it all the more unnecessary to waste time on that trivial, irrelevant detail.
Further info w.r.t actual regulations1 as provided by Broklynite in comments (tip of the hat to him):
To the best of my knowledge there are no hair dyes approved by FDA, period. This is because they are typically made using coal tar dyes and harmful. They get away with it as a cosmetic because the argument is that it is not supposed to be used where it touches the skin itself or the roots, and therefore isn't harmful. This is for all hair dyes, eyebrows are not singled out. However, the FDA does have regulations about colors which are permitted near the eyes specifically. But bleaching may be considered something else tho still fall under cosmetics. I would check the actual regulations.
This is a little bit complex, so please bear with me.
According to 601 (a) adulterated cosmetics of the FD&C Act, hair dye may contain coal tar dyes if they have a warning label which includes explicitly forbidding its use for eyebrows and eyelashes. According to ucm143066 on the FDA website:
"No color additives are approved for dyeing the eyebrows or eyelashes."
So long story short: no coloring eyebrows with dyes tho non-dye
Colorants may be used such as approved color powders (like makeup).
As to bleaching, the active ingredient in hair bleach is hydrogen peroxide, typically 30% strength (note that your home stuff is usually 2-3%). Hydrogen peroxide is on the FDA list of Substances Generally Recognized As Safe. However 21 CFR 184.1366 goes a bit more into detail that it refers to the use in food and cloth.
However, Since hair bleach at 30% is an openly dangerous chemical, I would suspect that it's use near eyes would no longer be considered a cosmetic but instead as exposure to a dangerous chemical, in which case OSHA may take a step in.
More or less, any company dumb enough to use it would open themselves to a lawsuit for hazardous work environments even if this is not covered explicitly by FDA. That said, it may fall under another FDA regulation or be an interpretation of a regulation which I am unfamiliar with.
On re-reading sec 601 I note it says:
"a cosmetic shall be deemed to be adulterated:
- if it bears or contains any poisonous or deleterious substance which may render it injurious to users UNDER THE CONDITIONS OF USE PRESCRIBED IN THE LABELING THEREOF..." (emphasis mine) which would seem to cover the unsafe use of 30% hydrogen peroxide near the eyes."
If the label says to use it near the eyes, the manufacturer gets busted. If the label does not say to use around the eyes and they use it anyway, HBO gets busted for using it.
FDA site on eye cosmetic safety found ucm048943. Note that 601 (a) explicitly states that hair dye does not refer to "eyelash dyes or eyebrow dyes."
So would be going with the more generalized harmful cosmetics regulations I think. Not a lawyer though, and not representing the Agency in this long series of comments, just pointing to publicly available information on regulations and Agency publications. Your mileage on this info may vary, and this does not constitute recommendations or legal advice.
I make no claims as to the veracity of my statements.
1. The responsibility for accuracy of these claims lies with Broklynite. I do not claim to have gone through the articles cited by him.
Different color hair can grow in different parts of the body, a dark haired man could have a natural blond beard or a blond man could have a dark beard.
With that being said I dont recall R.R ever actually describing the color of Daenerys eyebrows specifically so I would not call it a gaffe, I imagine it was a deliberate choice seeing as how I imagine it may be difficult to dye someones eyebrows and I'm not certain how good platinum eyebrows would look on camera.
It would be acceptable to say itis normal because these changes could really happen in reality, but when almost every character in GoT has different hair and eyebrow color (except for the who ever has black) then it just looks ridiculous. Anyways the solution is to find an actress with the natural color, they just weren't clever enough to think about it ;)