Thinning Bottled And Tubed Acrylic Paints

[malvern_man]

Hi all,

A question about thinning acrylic paints.

I have a good selection of acrylic paints, the bottled versions ( Vallejo and Citadel ) and the type that come in tubes ( from Hobby Craft ). I normally thin them down with water but I want to try thinning them with a matt medium.

Are all acrylic mediums the same or are some better than others?

Regards, Chris.

[Ian M]

Can of worms in 5,4, 3, 2, 1,

[Waspie]

I'll start!!!
The one thing I have taken from this site is experimentation. That is how I managed to occasionally get the correct mix. I have a method that works for me, but that's personal choice. Like you, I'm a newbie so not going to add much more. Trial and error - magic way to learn!!!

[Ian M]

I use mostly Vallejo and I started out using distilled water to thin with. (Our water is basically liquid chalk). But found it made the paint very fragile and normal handling during the build would damage the paint. Use the 'correct' Vallejo thinner now and all is well.
No rules without exception. I use Tamiya acrylics on occasion but thin that with Mr hobby self leveling thinners.
Not all acrylic products are cross compatible some are water base others solvent based and never mix those. Glup will occur.

[Waspie]

I use mostly Vallejo and I started out using distilled water to thin with. (Our water is basically liquid chalk). But found it made the paint very fragile and normal handling during the build would damage the paint. Use the 'correct' Vallejo thinner now and all is well.
No rules without exception. I use Tamiya acrylics on occasion but thin that with Mr hobby self leveling thinners.
Not all acrylic products are cross compatible some are water base others solvent based and never mix those. Glup will occur.

Something new learned!! I thought acrylic was acrylic!!!! That could have been disastrous!!!

[wasdale32]

You don't say if you're brush painting or using an airbrush so the advice may differ.

As far as the liquid paints are concerned you have to be very careful with different thinners/solvents - It would be good if someone could produce a matrix of compatible combinations but I've not seen a reliable one.

Trial and error (mainly error) seems to be the normal advice - but don't try an untested combination directly in an airbrush as that's a guaranteed route to stripping down the airbrush and cleaning out the "cheese" that will inevitably bung it up.

The issues I've seen are mainly with Vallejo Model Air paints which don't play well with some solvents. Also some solvents are "hotter" ( more aggressive) than others and can even attack the primer base.

Tube paints are a different challenge - most ART product manufacturers ( eg Windsor & Newton) produce their own formulated matt & gloss mediums ( and varnishes ) which are compatible with their own ranges. CRAFT paints are a different matter - they are usually cheaply made and even colours in the same range have very different composition.

[Guest]

I use mostly Vallejo and I started out using distilled water to thin with. (Our water is basically liquid chalk). But found it made the paint very fragile and normal handling during the build would damage the paint. Use the 'correct' Vallejo thinner now and all is well.

Do you mean actual thinner, or Vallejo’s “thinner medium”? The latter contains resins or whatever so that the paint doesn’t lose “bulk” when thinned with it, as it does when you just add thinner (or water).

I thought acrylic was acrylic!!!! That could have been disastrous!!!

There are essentially three kinds of acrylics for sale to modellers these days: alcohol-based acrylics, water-based acrylics, and acrylic lacquers. Don’t mix any of these with the other types, or use products intended for one with the other.

Tamiya and Mr. Hobby make alcohol- and lacquer-based acrylics, Vallejo, Ammo, MIG etc. make water-based ones.

[malvern_man]

Thank you all for the comprehensive replies.

I use water based acrylics 99% of the time, Vallejo and Citadel ( for brush painting as I don't have an airbrush ) From all of your replies it sounds like thinning paint isn't quite as straightforward as it sounds....so, for the time being I'll still use water. I've got gallons of deionised water as I use it for mixing up the products I use for car detailing ( another 'hobby' of mine )

Regards, Chris.

[IanW]

You don't say if you're brush painting or using an airbrush so the advice may differ.

As far as the liquid paints are concerned you have to be very careful with different thinners/solvents - It would be good if someone could produce a matrix of compatible combinations but I've not seen a reliable one.

Trial and error (mainly error) seems to be the normal advice - but don't try an untested combination directly in an airbrush as that's a guaranteed route to stripping down the airbrush and cleaning out the "cheese" that will inevitably bung it up.

The issues I've seen are mainly with Vallejo Model Air paints which don't play well with some solvents. Also some solvents are "hotter" ( more aggressive) than others and can even attack the primer base.

Tube paints are a different challenge - most ART product manufacturers ( eg Windsor & Newton) produce their own formulated matt & gloss mediums ( and varnishes ) which are compatible with their own ranges. CRAFT paints are a different matter - they are usually cheaply made and even colours in the same range have very different composition.

I am a big fan of the Windsor & Newton Galleria range of products, especially the Matt Medium.

I use it with artists acrylic paints for use in my dioramas, thinned further with distilled water . and a few drops of Galleria Flow Improver if required.

I have also found that the Galleria Matt Medium is a great improvement over using PVA glues for adding foliage - static grass, leaves etc as any excess does not show up so much as PVA can.

Only downside is that it is only available in larger size pots (250/500ml) as opposed to the smaller sizes ones most modellers are used to. Not a big problem as I just decant some into smaller bottles and the bigger sizes last a long time - am presently awaiting delivery of a 500ml pot as my existing one (probably 10+ years old) is running out.

I have found lots of other uses for it over the years - tents, tarpaulins etc.

[Tim Marlow]

Medium is basically paint without pigment. Different mediums give different effects. Matt Medium basically makes a more transparent matt paint. Glaze medium has flow improver incorporated into the formula so it can be put on thinly. Impasto medium makes paint hold its 3D shape….etc. Any water based acrylic should be intermixable with any other, but test first obviously.

The difference between paint brands usually comes down to the quality, amount, and particular consistency of the pigment. The cheaper the paint is the less pigment it is likely to have. Covering power and ease of handling will therefore reduce compared to a better quality brand. Cheaper paint may also not behave consistently when thinned because the pigment isn’t ground evenly.