Paint add ins, i.e. flow retarders, etc.

[Damas]

Hi Gents,

I paint using the advanced technique of take acrylic paint from pot, add to pallet, add water as desired, apply to model.  Repeat.

Can someone(s) please explain what all this malarky of paint retarders, paint thinners (I thought that was what water was? ), flow improvers, etc., is actually all about?  I keep hearing these terms but I have no idea about how they should be applied and what products would be used.

Also, if you do refer to any specific products, I'm in the uk.

[Mason]

Not sure about the relevance of such things, mate.
Never used anything like it myself and have always managed quite well with water too.

I am pretty sure Captain Blood does not either and his results speak for themselves.


Saying that, I do have a friend who uses this kind of witchcraft and swears by some of the products.
Supposedly it slows the drying process and allows longer for him to blend.
He does spend all day painting a cloak, though.....

[shredder]

I also don't use them, water seems to work fine for me but I'm no Picasso ;-)

I do sell a reasonable number of pots though (Vallejo Thinner Medium mainly) so obviously people do use them. I'd also like to hear the view from an expert :-)

G

[Nysse]

I've used the drying retarder quite a bit when having to paint with really small brushes. Comes in handy when you want to do really thin lines or edge highlighting. Without the retarder the working time with paint would just be far too short. For normal painting I don't really find it that useful. If you want to do a lot of blending it's good, but I'd rather paint with thinner layers or then use proper oil colours if I want a smooth transition.

Thinners come in handy if the normal tap water in your area isn't the cleanest. I've heard people having issues with chalky surfaces sometimes thanks to tap water that was used in thinning the paint. But I'd guess buying a bottle of water from the store and using that will be cheaper than thinner too I use thinners with my airbrush. Vallejo airbrush thinner is pretty much the same stuff that their airbrush cleaner is and seems to allow the paint to flow better than when water is used to thin.

[Vermis]

I like using flow aids, occasionally, when I want to get a smooth finish. (I find it difficult to do with white, for some reason) They break the surface tension of the water in thinned paint and help it to spread out evenly: fewer visible brushstrokes, no pigment clumping at the edges of watery layers, etc. Usually marketed as flow aid, flow improver or tension breaker for acrylic paints, though I have a few bottles of old Klear acrylic floor polish stowed away, that does pretty much the same. Not strictly necessary, but like a lot of not-strictly-necessary things it cuts down on the work and effort a bit.

I've no idea if vallejo thinner does the same thing, or what it consists of, without looking it up or trying it. (Might do today since I'll be round the model shop way) GW lahmian medium does seem to have a similar effect, though.

I particularly like daler-rowney's thick gel 'matt glaze medium', too. When I add that to paint, thin it down (with water!), and add a wee drop of some kind of flow aid, I can get pretty nice, silky washes. Sometimes better than GW's ready-made ones, IMO.
It does just what glaze mediums do - adds transparency to the paint while retaining 'body' and adhesion. Especially useful if you're thinning a wash way down with water. Not that I'm painting it on impasto, but it keeps it just this side of completely watery - helping to hold the pigment in even suspension, without dribbling, running and pooling everywhere, but without too much paint in it to prevent it being a proper see-through wash.
Then the flow aid takes the evenly suspended pigment and helps spread it out evenly. At least, that's my theory. My washes don't seem to work as well without one or the other, anyway. Doesn't seem to work as well with other acrylc mediums either. Or at least liquitex's basic matt medium.

Here's a pictorial explanation I whipped up ages ago. Look especially at the back armour in the bottom pic. That's one of the coat d'arms 'super washes' on the left side. It's used on the arm in the middle pic too, and it's not that much different in effect to the water-thinned, no-additive snakebite leather paint used on the face in the middle pic. No offence intended to CDA: just using it as an example of additive effect. It'd be okay for filling or lining the deepest cracks on a mini, but it's nowhere near the smooth gradient of the GW ogryn flesh wash on the back armour's right side, because it just doesn't have the (same amount of?) stuff to hold and spread the pigment evenly.



Retarders I haven't tried. I figure they're more useful for people who use wet palettes for mini painting, or wet-blenders. Nysse has an interesting point about small brushes and thin lines, though.

[Major_Gilbear]

First of all, just to be clear about what they do/are for, let's start by covering what paint is.

Paint is basically a very finely-ground pigment suspended in an acrylic binder. The acrylic binder stays wet whilst there is water in it. In addition, other additives may be present in order to give the paint other desirable characteristics (like workability, matte/satin/gloss finish, faster drying time, etc).

The more pigment in the paint, and the more finely ground it is, the more expensive the paint is. Model paint usually have relatively low pigment content compared to artists' acrylics, but the pigments are often much finer.

Metallic paint usually includes mica flakes, which is what reflects light and makes them appear shiny. The bigger the flakes, the "coarser" the "metal" finish appears. Sometimes, real metal is used instead of mica, and often there is a tint added to the flake-binder mixture to make the paint appear as gold or silver or whatever. Real metal is more expensive than mica in such paints, and the binder is sometimes formulated slightly differently too.

Now, each of the more usual additive products will affect one or more paint characteristics differently, and some don't play well together. Roughly grouping them, these are as follows:


Matte/Gloss Mediums

If you think of paint without pigment as "blank", then that's basically what these are - blank paint.

They come in a variety of finishes, usually matte or gloss, but do not change the consistency of the paint.

They do change the finish though - adding a touch of matte medium to regular paint gives the mixture a matte finish for example.

Adding these to your paint reduces the concentration of pigment in the paint, and effectively the paint becomes more transparent. This allows you to layer your colour(s) to build up a desired transition.

Mixing matte medium and gloss medium together causes the paint to immediately "coagulate" and spoil, so don't do it. Adding matte medium to gloss paint is okay, and gloss medium to matte paint is fine too. However, whatever is in the mediums themselves does not allow you to mix them with each other at all.


Metallic Mediums

These are a very small amount of binder with rather a lot of mica.

You add this to inks or to paints to make them "metallic". This works best if the pigment doesn't obscure the flakes too much, so adding them to ink or to a paint-and-ink mixture generally works best. You can also add these to metallic paints to boost how reflective they are, and to brighten them.


Glaze Mediums

Sometimes known as flow-aids, these are basically an additive that lowers the surface tension in paint to make it more runny. This improves the flow of the paint, reducing tide marks and streaks when you paint in thin layers. It also helps to keep the pigment more evenly distributed when you thin the paint.

Adding a drop of paint to a few drops of glaze medium plus a few drops of matte medium and some clean water allows you to make a GW-style wash in any colour you want.


Quick-dry/Retarders

Most craft/hobby/model paints are designed to dry fairly quickly so that painters can do multiple coats in one sitting.

Retarders slow down that drying process, giving you more time to work the paint.

They are useful if you have to freehand small designs or if you want a wash to dry slowly enough to allow the pigment in it to settle in a more graduated manner.

Retarders are often very gloopy though, and are hard to mix into paint. Pre-thinning them with clean water and keeping them in a dropper bottle makes them much easier to use. It also allows you more precise control on the amount of retarder added to paint (if you add too much, the paint will stay wet for days, and will be "tender" for days more).

I don't know of anyone using quick-drying additives with their model paints, but they are available for artist's acrylic paints, and might be useful if you want your paint to dry faster for some reason.


Thinners

Usually, this means clean water. However, adding a lot of water can make the paint take a long time to dry.

Some thinners are basically just alcohol (commonly used to thin metal-flake metallic paints, and also some of the Tamiya model paints), which thins paint and dries very fast.

Some thinners are a mixture of alcohols and water though, allowing you to really thin paints without increasing the drying time too much as a result.

Some thinners are also useful/used as flow-aids too.

For thinners, there is another reason that you might not just use water, and that is that if you thin the paint too much, you can "break" the binder's capacity to suspend the pigment properly within it. If this happens, it'll make the paint harder to work with - not least because many of the pigments will settle out of the paint pretty quickly then, and can even give you a "gritty" texture.

_______________________________________________________

Finally, some of the above can be used in other ways too.

For example, using a water and matte medium mixture over a gloss surface flattens the shine totally. This is useful if you want to hand-varnish in gloss for durability, but prefer a matte finish and don't want to re-varnish or spray over.

You can also gently brush some metallic medium along the edges of a painted metallic surface as a very delicate "super-highlight" too, although you will need to seal if if the model is for gaming because the binder in the medium is very very light.

I mostly use Vallejo's mediums, glazes, and retarders. However, Liquitex (an artists' acrylics brand) makes a superb matte medium and glaze medium that I know many people use - and a half pint of either will last you forever too.

It's worth researching into artists' acrylics brands (like Liquitex, Golden, Winsor & Newton, Daler & Rowney, etc) because they are not only often better value, but they also offer other products too. Some of the products like crackle medium or texture pastes might not be too useful for miniatures themselves, but instead might be really good for doing the bases with.

So there you go, a bit of a long-winded explanation, but hopefully that's helped you get a start on what the more common additives do.

[Mick_in_Switzerland]

Dear Major_Gilbear

Thank-you for the explanation - very useful

Mick

[Damas]

Indeed, thanks for the clear details, Gil.

[Vermis]

Glaze Mediums

Sometimes known as flow-aids, these are basically an additive that lowers the surface tension in paint to make it more runny.

Not in my experience...

http://www.daler-rowney.com/files/Acrylic-Glaze-Medium-Matt-Gloss.jpg
http://www.daler-rowney.com/files/Soluble-Varnish-gloss-Flow-enhancer.jpg

[Major_Gilbear]

Not in my experience...

http://www.daler-rowney.com/files/Acrylic-Glaze-Medium-Matt-Gloss.jpg
http://www.daler-rowney.com/files/Soluble-Varnish-gloss-Flow-enhancer.jpg

Depends on the brand, but many of them do in fact improve flow rather more than matte/gloss medium (even if they don't directly say so). Otherwise, you'd just use matte/gloss medium.

It is also worth noting that nearly all mediums improve paint flow to some extent simply by virtue of lowering the "concentration" of pigment in the paint mix and by extending the breaking point of the binder.

[Wirelizard]

I've chatted with the folks at my excellent local art supply stores a couple of time about the various mediums and whatnot, but never had a nice concise miniature painting focused explanation of them - thank you very much, Major Gilbear!

The only one I've ever used is gloss medium for water effects on scenery, but that's basically using it as acrylic gloss varnish at that point.

[Vermis]

Depends on the brand, but many of them do in fact improve flow rather more than matte/gloss medium (even if they don't directly say so). Otherwise, you'd just use matte/gloss medium.

It is also worth noting that nearly all mediums improve paint flow to some extent simply by virtue of lowering the "concentration" of pigment in the paint mix and by extending the breaking point of the binder.

Problem is that the other brands I looked at - Winsor & Newton, Liquitex, Golden - have seperate products for acrylic glazing and 'aiding flow'.

Acrylic glaze mediums, along with standard mediums and thinners, generally aid flow among their other listed properties, but they're not also known (or marketed) as flow aids. I wonder if it's at least partly due, as you say, to the fact they simply dilute the paint and pigment (though some glaze mediums seem to have slightly different listed properties to standard mediums, which is probably why they exist as seperate products), and I'd say that they just don't have the same detergent, water-tension-breaking ability as labelled flow aids, RE my own wash-making experience above. (When you see the little circle of foam, pigment and whatever race outwards, after dropping tension breaker into a thinned paint/glaze/water mix, you know it's doing something more!)

I've no idea if vallejo thinner does the same thing, or what it consists of, without looking it up or trying it.

I got some of this last week. I haven't tried it yet but I think the label is a giveaway: '100% acrylic resin'.