When to prime

[HackedDuck]

So I have heard that you should not spray prime your models if it is too humid? But why? And when is it too humid? Are there any other times I should prime models?

[Atia]

You should always prime your models, as it helps the paint to adhere to the mini (this is the important point), and also changes the tone of the base layer (darker primer will make it darker, white one brighter).

[Grotsmasha]

Humidity (or excess water in the air) will effect the finished quality of the spray. It is also best to spray out of direct sunlight, as this can cause the the painting to begin drying mid-air.

[Kastor Krieg]

Do not spray-prime over 65% humidity, over 30 and below 10 Celsius.

[Bryan Blaire]

Most cans in Farenheit will say between 50-90 degrees F, and no higher than 85% humidity. The humidity should probably be lower than that, closer to 60-70%.

 

The humidity affects the process because the solvents actually dry below the dew point, which causes a frosted effect. The heat will cause the droplets to dry before they ever hit your model, causing a grainy build up.

 

There are a couple of ways to deal with the humidity while drying: take it into an air conditioned space, use a warm box (can make one with simple plywood and an incandescent light - you don't need an actual heat lamp). Either should knock the humidity while drying down enough to keep it from causing that frosted effect.

[Major_Gilbear]

I was asked a while back a similar question by someone who lived somewhere hot, so (ahem) please allow me quote myself as I feel it still answers your question well:

Spray in the evening - where you are, the heat of the day dries out the air; when the sun starts to go down, the cooler air dries the paint more slowly (what you want for a smoother coat). Spray in shade or fading light if you can - the bright (and hot) sun will dry the droplets in the air as they travel to tthe model, and that's part of what causes the fuzz. In humid conditions, the droplets react with the moisture in the air as they travel to the model, also giving you fuzz.

Keeping the cans somewhere warm isn't automatically the kiss of death for them (as long as they are not cooking in 40C-plus heat or anything), but prolonged heat/cold tends to spoil their effectiveness - rattle cans are cheap and cheaply-made afterall, and are not designed to protect the contents for very long outside of more temperate conditions.

Using automotive sprays is generally better than hobby sprays too - they stick better, dry harder, and have more solvent in them (which helps coounteract the humidy and temperature a little whn using them, thus making them a little less sensitive). The cheap brands are good becuase they are cheap and if you have to chuck away a $3 can every month it's no biggie (compared to ruiing $50 of models anayway!). Just make sure that when you prime with rattlecan sprays, that you leave them to cure for a full 24 hours as a minimum. The extra solvent can take a while to fully leave the surface, even if it's touch-dry after half an hour.

Hope that helps!

With my comments here, please keep in mind that I'm a "do a job as well as you can first time around" kind of guy, as my time is limited and I always prefer to spend a little time upfront getting it right than corner-cutting and struggling/cursing later on - and sometimes that means spending a little more money too and waiting for a good day/condition to prime a batch of models. As with so much in life, planning goes a long way - even in a creative hobby!

With regards to whether or not GW sells real primer (since that is what a lot of people use and have mixed results with), or they simply a spray paint that they call "primer", please allow me to quote myself again from a different topic:

Here's MY personal gripe with GW sprays and such…

I've been painting a very long time. Over that period of time, GW has changed their paint line several times. Through each change, it seems to me that GW is not actually manufacturing the sprays, but re-branding another company's spray. That isn't necessarily a bad product, but over the years, I've desired a bit more consistency. If I go to the auto parts store and buy Dupli-Color primer, I'm fairly certain that it's still going to be the same stuff that I bought 2 years ago. That doesn't seem to be the case with GW. I want a consistent product each time I purchase it, especially when it has a premium price attached to it.

Exactly this, and I understand that it further varys depending on where you are in the world too (as I think GW tries to source sprays somewhat "locally" if possible).

Here in the UK, I have always found Halfords primers to be the best and most reliable. These are what the GW studio uses (or used to use), despite advertising thier own brand. And even though I don't think they name Halfords directly anymore, FW have always advised using non-GW automotive spray primers on their products.

This is because it's not just about cost vs coverage: the formulation matters, and these are sprays designed to give good results outdoors on bare metal; however, the GW primers aren't really designed to that spec. That's why getting a good finish from automotive primers is nearly always easier and more consistent in my experience, and why they bond better to the model (i.e., they don't rub or scuff off as easily - although things like spear tips and such will always be an issue). It's worth noting that they generally have more solvent too, and so can take a full 24 hours to cure completely and "shrink" fully onto the model.

As you can see, these sorts of topics come up quite a lot (and understandably so)!

Hopefully, that answers any questions on the topic for you - of course, if you still have more though, please ask away.

[Carlson793]

...and the effects of priming in different humidities:

50% humidity, 0-5 mph wind

Smooth, even surface

65% humidity, 5-15 mph wind

Smooth but uneven surface

65%+ humidity, no wind

"Primer celulite." Rough, uneven surface

[OrangeBob]

I'm with Carlson793, humidity is the absolute prime factor. I have refused to prime models in anything less than 60% humidity for 4 months now, and the results have been unbelievable. Of course, this new method tests my patience all too often when thunderstorms roll into town for weeks at a time...

[Carrack]

It is pretty much 60% + humiduty for the summer where I live, and I was a victim of fuzzy models the first time I primed in summer, it looked like my black primed models had been in a snowstorm, and the fuzziness bled through base, layer and wash. What I do now, is prime the models outside in a shoe box lid or something similar, than quickly take it into my air conditioned house. To keep the house from smelling like paint, and my kids from getting a hold of wet painted models, I place the box lid and models in a gallon ziplock bag, flatten out some excess air and seal it, then put the bag in my garage for a day or two. I haven't had any problems with humidity using this method, but obviously it's not suitable for large models or big batches.

[Cassian the Confessor]

I have the luxury of priming with an airbrush, which I do indoors - at any time of the year. I've found it much better than spray primer.

[Soldier of Dorn]

Because it screws with your models.

[Hrolf the Cunning]

Because it screws with your models.

Was that referring to priming with an airbrush or in high humidity?

[Soldier of Dorn]

 

Because it screws with your models.

Was that referring to priming with an airbrush or in high humidity?

 

 

Humidity. Sorry, should have been more clear on that.

[lhg033]

never had the humidity issue but you will also get the paint drying before it reaches the model/grainy effect if you spray from too far away (poor Eldar battleforce I had some 10 years ago will testify to this)

 

 

Major_Gilbear - which halfords primer do you use/recommend?

[Major_Gilbear]

never had the humidity issue but you will also get the paint drying before it reaches the model/grainy effect if you spray from too far away (poor Eldar battleforce I had some 10 years ago will testify to this)

 

 

Major_Gilbear - which halfords primer do you use/recommend?

 

 

I use this one; I normally prime grey.

 

I do sometimes use the white one as well, and I have also in the past used the black - both are also excellent. The matte black only comes in smaller 300ml cans though. (I know they do a red too, but I've not used this yet).

 

Finally, I have also used these:

 

Camo Green

Camo Brown

Camo Khaki

 

These are again smaller cans, and are more expensive too. However, they are very good paints, and have great colours for mass-spraying bases. The brown is very dark, and the green is fairly dark. The khaki is brilliant for sandy bases though. All of them are worth considering if you have a lot bases - they and the models can be primed separately, and then stuck together for painting.

[Carlson793]

And in case you weren't sure, this is what you really want to see when you have models to prime (SQUEE!!)