Thinning acrylic paints?

[Beatnik cryptek]

Ok, water works to a point, but I keep hearing about flow aids and mediums.

 

Can someone give me the basics on acrylic mediums for thinning paints and can you make them or have to buy them?

[Gederas]

Liquitex Flow Aid and Drying Retarder. If you're in the United States, you can easily get those at a Michael's store in the Paint section.

[Spacecow]

Medium is paint without the pigment. So adding paint to it helps it thin down better than water.

 

Every paint line has them and you can get them Matt or Gloss.

 

I actually use medium from a paint store. Cheaper for a big bottle. Same goes for my retarder. = a liquid that extends the drying time.

 

Flow improver is handy for airbrush or to add a dot in when you are free handing.

 

Hope this helps!

[Arkhanist]

Quick run down of the basics.

 

Acrylic paint is made up of water, acrylic binder, pigment (and usually matting agent so it dries matt-ish). As the water evaporates, the acrylic chemically bonds the pigment to the surface and itself. Adding water lowers viscosity and increases transparency - it makes it more runny and lowers pigment density. Too much spreads the binder too thin, and it causes problems with adhesion, as well as uneven pigment distribution.

 

'Medium' or 'thinner' is a catch all term for acrylic + water + sometimes extra ingredients - this is basically transparent paint without pigment. So gloss medium is binder and water. Matt medium is binder, water and matting agent so it dries, well, transparent matt.  so when you dilute paint with matt medium, you make it more translucent without otherwise affecting the properties or adhesion. Each paint company uses different mixes of acrylic binders, but they're all very similiar. So most of the time you can use any matt medium to dilute any paint; art company versions like liquitex, winsor and newton etc etc are generally cheaper per amount than hobby branded versions, but also larger bottles that will last years. Far cheaper than lahmian medium which falls into this category.

 

The exception is alcohol-added paints like scale 75 or tamiya, for those I strongly recommend using their own branded thinner medium. (alcohol allows more pigment density than water alone, but also interacts with generic binders in funny ways)

 

I mostly use liquitex airbrush medium (decanted into a smaller dropper bottle) any time I want to significantly thin a paint, as it keeps it paint like instead of  the effect too much water has. I don't bother when I'm just thinning for normal application on the palette with a drop or two of water. Even though it's branded for airbrush use, I find it good for base and layer paint thinning.

 

Flow aid makes paint, well, flow better. It also slows paint drying a little. Too much flow aid stops it adhering properly, so you shouldn't dilute with too much flow aid. Artist flow aid, such as liquitex comes concentrated so you need to dilute with water first (such as into a dropper bottle), for our type of paints you want a ratio of between 1-in-5 to 1-in-10 flow aid to water; more concentrated means you need less, but increases risk of overdoing it. I mostly use a drop in the airbrush to help stop it drying on the needle, but also usually add a little for thick, chalky paints such as white and off-whites so it goes on smoothly. Some types are toxic, so don't lick the brush if you do that when using flow aid. Vallejo do a pre-diluted version called flow improver that's ready to use out of the bottle.

 

Slow dry/retarder literally slows down the paint drying. This is used, again in limited quantities, mainly when doing wet blending or airbrushing. It does drastically extend how long the paint stays wet. I rarely use this, sometimes for awkward paints in the airbrush that clog far too quickly, though usually that just means I've used the wrong medium for thinning i.e. the alcohol thing I mentioned above.

 

Then you've got the special mediums which are often pre-made mixes of the above; glazing medium for example is usually some combination of flow aid and matt medium and possibly slow dry. For glazing, i.e. stretching a paint right out into a translucent glaze without affecting adhesion, I've started using instar water+ instead as there's something special in there that keeps the pigment evenly distributed in the thinned paint and is thinner than liquitex airbrush medium, but then I'm just lazy!

 

Contrast medium is something new; it doesn't behave like any of the mixes of the previous I've used before, and I've used them for years. It works extremely well at turning washes into super-washes that barely touch the upper surfaces, I'm sure we'll discover more uses for it.

 

There are various recipes for making your own wash or glaze mixes from a mix of water, matt medium and flow aid, I'll see if I can find them later if someone doesn't beat me to it.

[Rik Lightstar]

Any medium will reduce the opacity of your paint, you're distributing the pigment through more liquid.

 

Some will carry the pigment better than others, letting you choose if you want to create a glaze (evenly distributed pigment allowing you to tint an entire area) or shade (pigment contracting together typically in recesses).

 

All mediums also impact your drying times, they're either going to dry faster or slower and again depending what results you want you're going to want to experiment with this a fair bit.

 

Vallejo do a substantial range of mediums but you can also find other brands of mediums in art or hobby stores.

 

I tend to use:

 

Vallejo: Airbrush Thinner, Airbrush Flow Improver, Retarder

 

GW: Lahmian Medium, Contrast Medium (great with other paints)

 

Windsor & Newton: Acrylic Glazing Medium

 

And Water

 

They all have different uses and can be mixed together for different results too.

 

Rik

[Stoic Raptor]

Lots of good advice in this thread, so I'll add what I can.  I summed up what each of the types of solutions do in my blog article about thinning paints:

http://the-sage-brush.blogspot.com/2015/04/headhunters-thinner-recipe.html

[Jolemai]

Good thread so far. However, if I may highjack it slightly, what would be the best option listed so far to revive GW paints?

 

By revive I mean anything ranging from sludge to putty (so still some moisture within).

[Spacecow]

The exception is alcohol-added paints like scale 75 or tamiya, for those I strongly recommend using their own branded thinner medium. (alcohol allows more pigment density than water alone, but also interacts with generic binders in funny ways)[/endquote]

 

The scale 75 that I got is water based not alcohol.

[Gederas]

Good thread so far. However, if I may highjack it slightly, what would be the best option listed so far to revive GW paints?

 

By revive I mean anything ranging from sludge to putty (so still some moisture within).

I had some EXTRA T H I C C (by that I mean super thick and sludgey) Corax White Base Paint (brand new to boot :lol:) and I had luck with just adding about two large brushfulls of Lahmian Medium, which thinned it out nicely. Maybe try that?

[Arkhanist]

 

 

The exception is alcohol-added paints like scale 75 or tamiya, for those I strongly recommend using their own branded thinner medium. (alcohol allows more pigment density than water alone, but also interacts with generic binders in funny ways)

 

The scale 75 that I got is water based not alcohol.

 

Scale 75 do have water in them, and thin with a brush with water, but react badly to some thinners, specifically vallejo airbrush thinner when I tried to airbrush them - turned gummy, similar to tamiya. The official scale 75 acrylic thinner I bought because of that has a 'flammable liquid and vapour' warning on it. They thin with IPA or other alcohols, which not all acrylic react well to.

 

I'm pretty sure there's some alcohol in there, though I can't prove it.

[Arkhanist]

Good thread so far. However, if I may highjack it slightly, what would be the best option listed so far to revive GW paints?

 

By revive I mean anything ranging from sludge to putty (so still some moisture within).

 

Matt medium added in stages, and shaken hard, ideally with a shaker of some sort. Basically just so you don't overdose it on medium in one go. Most I've ever had to go was about a teaspoons worth, added 6 or so drops at a time. Lahmian is the same medium as GW use in the paint so is the most 'compatible' but I've found it works just as well with liquitex matt airbrush medium. I actually pre-dilute quite a few of my paints with medium when I first open the pot, they're so gloopy...

 

If it's gone extra-thick, i.e. approaching putty state, I usually add a little flow improver too, as it's started to bind in the pot and that will break it down again. IPA or vodka will have a somewhat similar effect, but you don't want to add much of any of them. Once it's gone full soft rubber, it's usually too late for recovery.

[Spacecow]

Ah you mean the thinner. Sorry, misread that. I Haven’t actually tried airbrushing with those paints (yet).

[Evil Eye]

Has anyone tried thinning GW paints for an airbrush with Mr. Aqueous Colour thinner? I love their lacquer thinners (they work really nice with Tamiya and other alcohol based paints too which is nice) so I imagine it should be pretty top notch. It's for their water-based line so I assume it'll work- I need to run some tests before I actually run it through an airbrush.

[Bung]

 

 

 

The exception is alcohol-added paints like scale 75 or tamiya, for those I strongly recommend using their own branded thinner medium. (alcohol allows more pigment density than water alone, but also interacts with generic binders in funny ways)

 

The scale 75 that I got is water based not alcohol.

 

Scale 75 do have water in them, and thin with a brush with water, but react badly to some thinners, specifically vallejo airbrush thinner when I tried to airbrush them - turned gummy, similar to tamiya. The official scale 75 acrylic thinner I bought because of that has a 'flammable liquid and vapour' warning on it. They thin with IPA or other alcohols, which not all acrylic react well to.

 

I'm pretty sure there's some alcohol in there, though I can't prove it.

 

 

I have used Vallejo Airbrush Thinner and Scale Color together without problems in my Airbrush.

 

I had more problems using Vallejo Colors with other thinners, mostly alcohol based ones until i found out that Vallejo Colors dobt like alcohol cause the paint will try faster and the pigment will turn to flakes.

 

Personly i switched to Createx High Performance Reducer for water based acrylics for airbrushing and for problem paints to AK Interactiv Extreme Metal Cleaner and Thinner (i use the extrem Metal Colors too, they are enamels like Alcad 2).

 

For brush painting on my wet palette i have to try Instar Paint Water+ (no joke like GWss Warter). i ordered it, but i havent got to paint much the last months.

https://shop.instarpaint.com/waterplus/

[Arkhanist]

FWIW, I'm not the only one that's had issues with scale 75 and vallejo airbrush thinner. Maybe it's only certain paints in the range, but I've certainly had a much happier experience (specifically the blues) since switching to their own thinner. Will probably give my liquitex a go at some point as suggested in that thread since I already use it for brush dilution!

 

Can definitely recommend instar water+ though. No idea what's in it, but got a sample bottle as part of my asset drop sub, and it does what it says on the website regarding keeping the pigment evenly spread when heavily thinned, much better than vallejo glaze medium IMO. It is very fluid so I still use liquitex medium for basic thinning (and thinning in the pot) which is a bit more viscous which helps with brush control for me personally, but you could definitely switch to it as a general pupose thinner and supposedly it also works well as an airbrush thinner though not tried that yet.

 

Contrast is my new go-to for thinning washes and making them more 'wash like'.

[Bung]

Personly i prefer a thinner i could use for all colors of one sort water based acrylics etc. 

I started to use the Createx one i mentioned above after switching to their Candy2O range for candy coats.

 

Thanks for the insight with water+ i will used the next time i get to painbt with a brush.

[Spacecow]

I’m guessing you would encounter the same issues with warcolours then, given that both they and scale75 use a gel medium.

 

I use Royal Talens Amsterdam mediums/ retarders. There range is extensive and high quality. So far no issues with them.

[Aramis K]

Good thread so far. However, if I may highjack it slightly, what would be the best option listed so far to revive GW paints?

 

By revive I mean anything ranging from sludge to putty (so still some moisture within).

I've had some luck adding a few drops of lahmin medium and a stainless ball bearing and lots of shaking. But it only works when it's thick - some of my pots went more solid like putty with thin liquid floating on top. Never managed to save those. So now everything gets a ball bearing from day 1.

[Stoic Raptor]

When the paint is a solid blob, nothing will save it.  That's no different than when it dries on a model.

[Quantum]

Related to the original post I have a question:

 

What is a good way to prepare citadel paints for long term storage, so that you can use them quickly after opening the pot.?

 

For the first time in years I've started painting again, and I have discovered that many of the paints I've used have degraded in the meantime. Some have dried out completely, but for many others the paints have separated the pigment and water, so that it has formed hard blobs underneath the water.  Still others are mostly okay, but part of the paint has formed hard crusts on the inside of the pot. Would the addition of some paint thinner before I put them in storage have prevented these from happening? 

[Fajita Fan]

Anyone know the practical difference between Vallejo glaze medium and matte medium? I bought both and they feel the same but there has to be a reason they’re sold separately.

[Spacecow]

I don’t have Vallejo mediums for that. But what it should do next to the thinning down is , is improve the transparency and flow of your paint. If you get the Matt it will help it dry Matt. There might be some dry retarder in there too ( not sure as I don’t have the Vallejo one.)

[Arkhanist]

Related to the original post I have a question:

 

What is a good way to prepare citadel paints for long term storage, so that you can use them quickly after opening the pot.?

 

For the first time in years I've started painting again, and I have discovered that many of the paints I've used have degraded in the meantime. Some have dried out completely, but for many others the paints have separated the pigment and water, so that it has formed hard blobs underneath the water.  Still others are mostly okay, but part of the paint has formed hard crusts on the inside of the pot. Would the addition of some paint thinner before I put them in storage have prevented these from happening? 

 

This is alas one reason why you see a lot of people not fond of current Citadel pots. I have 20+ year old citadel original tall fliptop pots that are still perfectly usable that have had little or no thinning ever. The current citadel pots don't seal fully, the water slowly evaporates and it all starts chemically bonding inside. Diluting the paint in the pots with additional medium before storage will delay the onset of this process, but not eliminate it; which means you have to go through the set every year or so, revamp it with medium and mix the hell out of it.

 

The old screw-top pots were even worse, I haven't had a single one of them survive, but the current 'bolter shell' pots are almost as bad, I only have a couple pre the current range than survived my hiatus. The only real way to prevent this is to decant them into decent quality dropper or fliptop bottles that actually seal properly, or store entirely unopened paints - and even that isn't enough sometimes.

 

The ones with hard crust formed inside the pot but with still liquid-ish paint are recoverable with a bit of matt medium, a good shake, and maybe a little flow aid to help get it painting smooth again. The solid ones and those have that formed a solid lump under the expelled liquid (which will be a mix of water and unbonded medium) are very likely unrecoverable I'm afraid.

[Stoic Raptor]

Actually, you can keep the new pots from drying out, it just takes a little maintenance.  It's inevitable that paint gets up into the gasket in the lid and around the rim.

I use a panel scriber every now and then to clear away that stuff, and the lids seal nicely.

[Fajita Fan]

Pro tip: if you get a second job you can afford to replace your GW paints as they quickly dry out.