Help with washpin wash

I'm mostly a ship guy, so am NO expert on most things weathering, but - what kind of gloss coat did you use? If it's an enamel gloss coat, Tamiya Panel Line Accent Color doesn't play well with it - you're basically putting enamel on top of enamel. That could account for the "diffusion" of the panel line accent onto the other surfaces where you don't want it to go.

My 2 cents.

Yup...what mfsob said.  Tamiya Panel Line Accent needs to go on over an acrylic glosscoat, and even then its a crapshoot as to whether or not its going to go right through that and attack the paint underneath.  Normally with a pin wash, you're going to be going back over those areas with a Q-Tip that is just barely damp with whatever thinner works at removing the excess to clean it up.  In the case of Tamiya Panel Line Accent, that would be enamel thinner...which also might go right through whatever clearcoat you used and damage the paint underneath.  If it were me, I'd clean up the tiny portion you've already done and then switch over to Flory Wash.  It is water/clay based, so the cleanup of the excess is done with a Q-Tip or little sponge that is just barely damp with plain old, completely safe, water.  It takes all of the stress, guesswork, and extra steps out of the weathering process.

Also, you might take a look at the Techniques forum in the Tools, Techniques, and Reference Materials group of forums.  Washes are frequently discussed in that forum.  There are some real gems of forums in that group.  Particularly good  is the Painting and Airbrushing forum.

I used Future floor polish as the clear coat.

I think it's not eating through the clear coat at the moment so far, but just somehow the panel line wash doesn't seem to stay on the edge where I want them to be. They look perfect when I just apply them and while wet, but before they keep 'creep' out from the corner before they dry up for some reason

Panel line washes will almoost always creep out from where you want them, that's why you use a Q-Tip dampened with paint thinner to clean up the excess.  

Just dip the Q-Tip in the paint thinner, and then use a paper towel to dab it on until you get most of the thinner out of the Q-Tip.  Then you just make light, quick wipes with the Q-Tip to remove the excess, while leaving the accenter stuck in the recess behind.

I used the Tamiya Black Panel Line Accenter on this one, over a Future clearcoat, with Tamiya AS-20 spray lacquer as my base color.  Cleaned up the excess with a combo of Q-Tips with paint thinner, and an old, ratty toothbrush in the really busy areas.

I like to use water-based acrylics for my washes, because I can use a cotton swab damped with water to remove the excess, as EagleCash described above.  And the water doesn't attack the Future I use for gloss-coating.

Unfortunately, gloss-coating can reduce the likelihood that your wash will run out via capillary action, but it seems there are always still tiny imperfections in the surface that the wash flows into.  In any case, removing the excess before it dries is a good step to add to the process.

I have experienced this exact issue. I have seen it with Future, Model master acrylic clear, you name it. It actually was worse with higher gloss clears. I recently watched a video where the builder actually thins his Tamiya Panel Liner with odorless mineral spirits. I will be trying this next time I use it.

I don't think the thinning agent will make much of a difference.  If the surface has tiny imperfections in it, there will be some bleed.  I think EagleCash's tip to remove the excess as quickly as possible, before it has a chance to bleed a lot, is probably a better step against that.

Yup, or just use Flory wash and eliminate all of the guesswork.  I'm using Flory exclusively for panel line washes now.  That stuff you just slop all over the model with a large brush and then clean up the excess with sponges, Q-Tips, or even clean paintbrushes dampened with water.  You can even literally leave it on for months or years and when you finally get around to removing the excess, it will come off easily from the spots you want to remove it from.  Its compatible with any kind of paint or clearcoat since it uses no solvents of any kind.

Eaglecash867

Yup, or just use Flory wash and eliminate all of the guesswork.  I'm using Flory exclusively for panel line washes now.  That stuff you just slop all over the model with a large brush and then clean up the excess with sponges, Q-Tips, or even clean paintbrushes dampened with water.  You can even literally leave it on for months or years and when you finally get around to removing the excess, it will come off easily from the spots you want to remove it from.  Its compatible with any kind of paint or clearcoat since it uses no solvents of any kind.

 

I have a different brand but it is a clay wash as well. They definitely come in handy when you use it as you describe. Sometimes though, you need a sniper instead of a nuke, LOL!