Good resist for hand filling in pours?

[Dijital]

I'm working on a design that has a fairly high power buck converter on the board. Given that I am using lots of large pours in the PCB layout. I can only do toner transfer though, and I don't want to deal with the headache of trying to get all those vast swaths of ink to transfer, nor do I want to use that much ink anyway. So in my design I laid outlines of the pours, and plan to fill them in by hand when I do the transfer.

In the past I have used a sharpie to touch up traces, but never to fill areas. So I am weary of it's ability to work in situations like that. Can anyone recommend a good ink or marker I could use? I looked at some resist pens, but they are relatively expensive and don't have the best reviews. I wouldn't be opposed to using a paint brush if necessary, finer detail areas I could just have the printer fill in.

Usually I etch with ferric chloride, but I also have sodium persulfate i could use.

[sleemanj]

Try the staedler permanent special, looks like it gave reasonable results in this video...

https://youtu.be/BMtYoMiKvMg

[rdl]

I've used model paint from the hobby shop and nail polish. Both worked well. I wouldn't use any that are "water-based" without testing first. Most are fairly waterproof when thoroughly dry, but better safe than sorry.