I’ve had quite a few people on here commenting and asking
about my Object Source Lighting (OSL) effects, so I thought I’d put up a quick
tutorial on how I go about it.

It’s pretty simple to do the way I go about it, and well
worth giving it a try, as it can really make a model pop!

There are 3 ways to do OSL- with and airbrush, with a wet
approach, or by drybrushing. The
airbrush is by far and away the best, but they are expensive, and actually have less application for dwarfs than some other armies, so if you don’t own one, I wouldn’t bother just to do OSL. I manage
without one. A wet highlight is very good, and this is the approach I’ve seen used a lot on how to videos on youtube- it produces a beautiful translucent finish that allows the painting underneath
to come through, and looks very realistic. However, it takes absolutely ages, many many layers that all take time to do and time to dry. It’s also much harder to do well, and very easy to mess up.
Since OSL is the last thing you do to a model after it’s already been fully painted that can mean a lot of time spent stripping and repainting. The drybrushing approach doesn’t produce quite as good an effect- it works perfectly fine for 95% of the time, but on certain points such as going over fine details picked out in different colours, and particularly light hitting gemstones, it’s not so good. It will still look absolutely fine at battlefield ranges, and even when examined up close is perfectly acceptable, but
will not have the same quality that a wet approach gives. However, it’s a lot easier, and far far
quicker. I always use the drybrushing approach, and then touch up with wet blends, and that’s what I’ll explain here.

Before getting on to the actual painting I’ll go through a few other considerations.

Firstly, like a lot of painting techniques, it’s best used sparingly- if you start doing glowing light effects on every single trooper it can take over from your colour schemes, and make the army look really bright
but unfocussed- a few bits here and there to pick out character and so on can work wonders. I like to include OSL on one war machine of each type- I find that when I deploy 3 different cannons
it’s easier to remember which one has which runes if they have subtle differences.

Secondly, it’s best to decide whether or not you’ll use OSL on a model before painting it, as it can guide your choice of colour schemes. It works best on models that are painted with simple colour schemes of neutral colours- too many bright colours can clash with the ‘lighting’. So if you know a guy is going to be holding a glowing rune axe casting light on his sleeve, it’s probably best not to give him tartan cloth or bright contrasting checks. The more OSL you’re going to do, the plainer the colours on the model should be.

Finally, the colour of the light is important. Too many different colours of light can make the army look uncohesive in the same way as too many different colours of uniforms. With my Dwarfs I actually only
use red light- this helps the army hang together without too many different colours going on. Certain colours of light are also easier to do than others; Red and blue light is very easy, green slightly less (this is because the blends of colours needed to lighten green can often end up changing the tone,
meaning your reflected light can be a different shade from the emitted light, which looks odd). Purple is fine, but works best as a dim glow, unless you want to make it pink. White light is the hardest of all- I’ll treat that in a separate section.

So, onto the actual painting. For this example I’m going to use a miner. As he is going to be part of a
unit potentially up to 40 strong, and they are all going to have OSL, that’s going to be a hell of a lot of reflected light. Therefore I’ve decided to make their ‘natural colours’ as dark and plain
as possible. Also, I’m going to keep the light fairly dim. Why? Well firstly a whole unit painted with really bright light will look like they’ve tunnelled into a rave, and secondly, really bright light coming off a model should reflect onto the guy next to him- if I do that however they’ll all need to rank up exactly the same way each time I use them or it will look odd. Therefore I want the light to be dim, and only touching the guy whose candle it is.

Now, when I paint, I start with a black undercoat, put the base layers on, and shade it with a black wash, and then build up the highlights over that. Here’s my guy before highlighting:

The next step is highlighting. Note that at this stage I’m talking about highlighting the various parts of the model in the colour that you want them to be, not talking about coloured light or anything! So if he’s wearing a blue coat, start with dark blue and work up to light blue as you would normally- I’m talking about the position of the highlights here, not their colour. Now normally when highlighting, it’s natural
to put the highlights on the upper surfaces, called zenithal highlighting, and keep the lower surfaces in shadow, as we expect the light to be coming from above, but when we add in a second light source, that may not be true anymore. It depends on the relative brightness. If you picture a dwarf in a black mine where the only illumination is a candle on the floor in front of him, it would be the top that is in shadow, and the underside that is strongly lit. If we take the roof off the mine and allow the sunlight to come in though, the light form the candle will be overpowered by the sunlight, and so the dominant highlights will revert to being on the top, with only a faint trace from the candle. So before you highlight your model, decide which light source will be brightest!

If it’s a dwarf lord carrying the most mighty death dealing rune axe known to man, glowing white hot and shooting out incandescent bolts of flame, that will probably be the primary light source, drowning out the ambient light, so highlight the model as you would normally, but treating the axe as the ‘top’ of
the model- bits facing the axe do brighter, bits facing away more in shadow. Areas on the other side of the model from the light source don’t need to be in total dark shadow though - remember they will still be getting light from the sun as well, we just want to give the impression that it is drowned out by the axe’s light.

However, if it’s a guy holding a small candle, the candle is
probably being drowned out by the sun, so highlight zenithally as you would
normally, and add the candle’s light in afterwards.

Remember this will also have an effect on other lighting tricks you may be using, for instance gemstones. Normally you highlight a gemstone at the bottom to give the impression of translucency, but if the bright light is coming from underneath, you’ll want to paint it upside down:

Anyway, in the case of my miner, I want his light to be dim,
and it’s positioned on top of his head anyway, so all of the light is coming
from above, so I’ll highlight him zenithally as normal:

So here he is, otherwise finished and ready for OSL. I’ve actually already given him a quick spray with Purity Seal. By the way, I’ve noticed a tendency for people when they paint flames to start them red at the bottom, working up to a yellow tip. A real flame is brightest yellow at the bottom, and works up to an orange tip! And red should never appear on the flame itself, as flames only burn a cherry red colour if there’s some kind of chemical burning- yellow to orangey yellow should be the extent. I paint the
flame Yriel Yellow, then hold the model upside down and ‘blob’ on Bloodletter glaze, allowing it to run down to the tip and bead there a little, before arranging a couple of paint pots so that I can hang the model upside down with the base resting off the tabs on the pot’s lids.

Now with OSL, it is vital that the brightest part should be the source of the light! The reflected
light should always be darker than the source. The only areas of reflected light that could be done as bright as the source should be metallic parts that are right up close to it, and even then I
try and make it dimmer. It’s also important to keep the colour as close to the source light as possible. So for a yellow flame, it will cast reddish orange light, but not pure cherry red. Any pure red light will look unnatural, like it’s coming from a laser pen or something!

The first step is to determine the limit of the reflected light. The brighter the source, the further the light will be cast. The dimmer the source, or the brighter any competing light sources, including ambient
light, the shorter the distance it will cast. So for a candle on his head, if he’s out under the sun the candle light will probably only reach around his head and a bit of his shoulders, but if he’s in a dark mine it will be showing up right down to his boots, and casting deep shadows underneath him.

Once you have determined how far the light will be cast, you want to look at each area before you paint it from the point of view of the light source. See what parts are visible, and what parts are in shadow.
It’s vital that you get this part right, or it won’t work. Remember OSL is kind of tricking your eyes,
and your eyes are very good at telling reflected light from emitted light- too many little inconsistencies and the illusion will completely shatter.

Start with the darkest colour light. This will look like the dimmest, and therefore is suitable for the areas at the limit of the light’s range. For this model I used Trollslayer orange mixed with mephiston red. Drybrush very lightly over the areas to get the light, being careful to keep in mind where your shadow lines are and not let any paint go into these areas. It’ll look odd when you try it for the first time, but have courage and persevere!

Now add the next layer. Here I’ve gone to neat Trollslayer- you could do more progressive mixes,
but it isn’t usually necessary unless you’re doing it over a large flat area. Keep this layer closer to the
source, leaving an area of your first, darker shade visible at the limit of the light’s range. Keep the drybrushing very light! With OSL you can always add more, but it's tricky to remove it if you do too
much. A very light feather over it, then stand back and have a look, and add more if needed.

You can see here I'm not putting any glow on the back of his pick, as it is shielded from the candle and therefore in shadow.

Now I add Trollslayer with Yriel Yellow mixed, and I’m working it over even closer to the source, then finally, a very light pure yellow highlight on the areas closer to the flame:

After this stage I decided I wasn't too happy with it as (like often happens) I'd gone a bit to far and his neck shield no longer looked metallic, plus his face was catching more light than it should given the angle. No biggy though, a little touching up on his face and the candle sorted those areas out. I touched up his helmet and neck guard and also his pick. When touching up mettallic areas that you've already gone over with drybrushed red light, it helps to really water down the metallic paint, and blend it in carefully ('spit blending'). I pulled it back to the light looked much dimmer, then once again extended the reflected light, but this time with careful highlighting with very watered down oranges and yellows. One trick to remember here is that light often 'glints' along metallic edges, making sharp elongated highlights rather than a diffuse glow, so I traced out the lines of the pick in fine yellow.

And there you are!

One last important point to note here is about the material the light is hitting. Metal reflects light very well, cloth and wood less so, hair catches light easily, but skin tends to absorb a lot of the colour from light. Taking this into account will make it look more realistic, and the easiest way I’ve found is by playing with the range of the light. At the furthest distance from the source that the light is reaching for your brightness, treat metal as catching the light, but not other materials. A bit closer to the source and wood and hair catch the light too, but they catch the light as metal did at the further range, while at this range the metal reflects more strongly, and therefore brighter.
Here’s an example:

Here we want to take account of the different materials the

light is reflecting off on this wooden war machine base with metal bands.

So the brightness and range is extended further on metal
areas than the wood. Done right, this
will really help to sell the illusion.

So there you have it! It’s well worth trying this technique, it’s not hard and will get you painting respect down the local Games Workshop! If you’re nervous about trying it on a model get a piece of old sprue,
and make one bit glow and try and get the rest of it to look as if it’s catching the light. Once you can do it on a sprue, you can do it on a model.

Good luck!