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Is there a way to revive old citadel paints? I tried water and it's working, but any other ways?

Water will work... to a point. Beyond that point you need acrylic medium. Art stores should carry it.

lliu wrote:
I tried water and it's working

If it ain't broke, don't fix it.

Search was buggy, so I couldn't find the more in-depth discussions that I know have cropped up, but there's a bit more info in this relatively recent thread.

http://www.dakkadakka.com/dakkaforum/posts/list/0/611852.page#7144657

Bit of detail over there...missed the thread you had linked to Oadie...been busy with stuff and stuff.

The basic process for an acrylic paint to go from liquid to solid is like so:

You apply it to a surface (or leave the cap off...have a bad seal on the bottle...).

The paint skins over. This happens rather quickly. The very top layer of paint has the solvents evaporate and the nature of the acrylic polymer chains starts to pull together at the surface. Bottles of paint that are half full or less can skin over as solvents evaporate within the bottle itself.

The solvent evaporates completely. This is going to be something like water, alcohol or other fluid/combination of fluids to keep things in suspension. Paints will be "dry to the touch" at this point. You can still revive these paints with just solvent (water in many cases).

The paint coalesces. This is the conventional cure point. The long acrylic polymer chains have coiled up and are all a twisted mess of hooked tails. Normally it takes about 3 days for an actual paint job to get to this point - bottles will vary, and provided that the cap isn't left off entirely - it can take years to happen.

The acrylic chains begin to cross link. When they are in suspension - they are long stringy bits. Once they fall out of suspension and coalesce, they form a pretty strong film. It can not be broken without damaging the acrylic chains (read - water won't work). Over a significant amount of time though - the acrylic chains will actually chemically fuse to each other. Certain paints are designed to crosslink faster (poly acrylics and catalyzed paints...as well as your oils and enamels). When it gets to this point, you can chemically dissolve the acrylic or pulverize it and introduce new fresh binder. Depending on the specific formula used in the binder, it can take from weeks to years to reach maximum film strength (able to be aided along with things like heat or UV light...).

So - the question then ends up being where are your paints?

Hard to say to be honest - at least without some hands on practice. One rule of thumb though is that most fluid acrylics are around 50% solvent and other junk that will evaporate out of them. This means that if you take a full bottle of paint, pop the cap and leave it sit for a month or so...it should dry down to a puck of dry paint that is roughly half the size of the full volume. By looking at the amount of paint left - you can generally gauge if you have an issue that can be solved by adding water or if more drastic measures need to be taken.

Not to worry - I've bookmarked both this and the linked thread for future use. This question has been cropping up, recently, so it'll be nice to be able to explain the chemistry without having to spam you with PMs or hope you happen to come across the thread.

I need to just write up an article and have my friend proof read it to make sure I have all the particulars down...or bug him to write one and then do a cliff notes version of it.

He is working for PPG now, so when I have a paint question I tend to hit him up - but I still have to remind him that while the post grad level information is interesting...I am much more interested in the applied chemistry of the processes.

Thanks for all those answers, I will search for some acrylic medium. Don't forget, all posts are still very very welcome.

So recently got back into the hobby after a break since 3rd. Tonight I spent going over my tools and paints. 28 of 30 of the new GW paints had dried out over the last 5+ years, but all but 2 of my 1980's era citadel paints are still liquid. Funny really.

Commisar Marbh wrote:
So recently got back into the hobby after a break since 3rd. Tonight I spent going over my tools and paints. 28 of 30 of the new GW paints had dried out over the last 5+ years, but all but 2 of my 1980's era citadel paints are still liquid. Funny really.

I've seen similar observations previously. It would seem very old Citadel paints sealed better.

As someone who also just got back into the hobby after about 8 years off, I just wanted to weigh in that I still have a bunch of late '90s Citadel paints (that cost $1.75 back in the day!), and they're all still perfectly liquid. The later GW paints I bought with the screw-on lids? Yeah, those are all completely rock-solid dried out, far beyond any possibility of recovery. Sometimes that saying "they don't make them like they used to" really does apply!

Yes, that phrase is definite.