Pen marks are stains, so they need to be sunfaded. That link that Strawberry supplied has some instructions, but be sure to check in often, as sunfading is much more practiced on G1 and some have reported issues while attempting to sunfade G3.
i curl hair using straws and bobby pins. let it dry, then pull the straws gently out.
boiling water and a fish knife against the plastic "pores" gets the ingrained dirt out
strong chemicals like acne cream or bleach are a NEVER
What about sun fading G4?Same method, just keep close watch.
So I'm guessing wet the hair, maybe condition it and put the hair around the straws, letting it dry out?You got it! A fish knife is a non-serrated yet sharp knife. Google has lots of examples. You can use scissors or a finger nail as well.
I can understand the boiling bit, but may I ask what a fish knife is? Never heard of it.
What is in Sard Wonder Soap? It sounds like it's bleaching your ponies, which can be a very bad thing.I cannot for the life of me find an ingredients list (likely because I don't have a VPN to set to Aussie) but someone said it has "non abrasive materials"? Makes me think if it's like oxiclean.
Here are some photos of the fish knife I use. As you can see it's handy for getting to those hard to reach places on a pony and is also lovely when you are deflocking:
Images underneath spoiler out of respect to those who have seen them before :)