Ratio for thining paint

Bgrigg wrote:

MusicCity (where has he gone to? Probably out riding his motorcycle!!) has some excellent articles about this subject on his website. I'm sure he won't mind if I link them here.

I'm still around, just don't have much to say.  And, Bill, you are right in that I certainly don't mind if you link to them.  I don't necessarily agree that they are "Excellent" since they are just my point of view, but you are certainly free to post links to them any time you wish.

As to the bikes, it's been kind of cold and wet around here so not that much riding the past couple of months.  I am flying to Arizona in a few weeks to ride around the desert for a week and enjoy some warmth and sunshine though.

Good advice

I've just ordered my airbrush, compressor, paints, etc.

This is my first airbrush, so I imagine getting a lot of practice.

I'm basically painting to protect my working model, so I want as thick coats of paint as possible. Of course, as has been alluded to already, having 4 thin coats to equal 1 thick coat is probably my safest strategy as I can always add a another coat easily, instead of pulling out my sandpaper.

Right now, I'm ordering many bottles of paint and saving all my juice, soda, and water bottles :)

thespaniard180 wrote:

Or if the paint was too thin, if your compressor was set low or you used very little air, couldn't you still airbrush just fine...or at least manage?

How thin is too thin? In practice, when using a double-action airbrush and a well trained trigger finger, very thin paint isn't a problem. Just lay it down in multiple thin coats and don't try for "one pass" coverage. (This is a good practice anyway.)

I primarily airbrush Tamiya acrylics and tend to thin much more than conventional wisdom (frequently quoted as two parts paint to one part thinner) dictates  - Tamiya's pigments are actually quite dense and for airbrushing, the paint holds up to thinning quite well - actually it's difficult to over-thin Tamiya acrylics.

I don't actually measure with any sort of accuracy how much thinner I add - paint viscosity varies "in the bottle"  for many reasons and generally I just eyeball my mix. If I were to try to quantify it, I'd say I use anywhere between one to four parts thinner to one part paint, depending on what effect I'm trying to achieve, (eg. very thin for base coats)

It's much easier to airbrush in thin coats and add more if required than it is to hit it hard and then have to remove paint if you lay it down too thickly.

 

thespaniard180 wrote:

How do you know if you've thinned too much, or your paint needs more thinning? Let's say your paint is a little too thick, but couldn't you just increase the compressor PSI and/or use a different needle/nozzle combination or something?

To a degree you possibly could, however if you force overly thick paint onto your model through brute force, you won't get nearly as nice a finish.  It would likely be thick and pebbly.  I don't think there's any reason to try an compensate too thick paint when it is easy to add a bit of thinner to fix it.

thespaniard180 wrote:

Or if the paint was too thin, if your compressor was set low or you used very little air, couldn't you still airbrush just fine...or at least manage?

The downside of using too little airpressure is that the paint won't atomize very well, giving you big paint droplets.  Oddly enough, you can use this to make an effective mud splatter look for weather tanks and other vehicles, but it is not the best way to paint.

The trick is to keep some scrap plastic handy, and test spray on it before shooting your model. If your paint is too thick, simply add thinner until you're good.  If the paint is to thin, you might be able to add some more paint to get it right, although often adding more paint is an exercise in futility because you would need to add so much paint, that you're better off draining some of the overly thinner paint.

If you're simply laying down a base coat, you might be able to compensate for your overly thin paint by moving your airbrush away from the model, possibly increasing the air pressure a bit, and making sure that you keep your airbrush moving fast enough while you paint to avoid build-up and runs.  That lays down a very thin coat of paint, and will likely need two coats, but the end result is perfectly acceptable.

Andy

Thanks for all the great help guys

Paint that is thinned too much just doesn't cover very well. That's usually your first clue. It also tends to "spider" more. Trying to adjust an airbrush to use over thinned paint would be nigh well impossible.

Paint that is too thick is far easier to thin than to correct an airbrushes operation. MusicCity (where has he gone to? Probably out riding his motorcycle!!) has some excellent articles about this subject on his website. I'm sure he won't mind if I link them here. Admire his work (he hasn't updated in a LONG while!) and then scroll down to the bottom of the webpage for his articles. Pay particular attention to the thinning and air pressure articles!

How do you know if you've thinned too much, or your paint needs more thinning? Let's say your paint is a little too thick, but couldn't you just increase the compressor PSI and/or use a different needle/nozzle combination or something? Or if the paint was too thin, if your compressor was set low or you used very little air, couldn't you still airbrush just fine...or at least manage?

Just to add to Bill's excellent advice on thinning to a 2% milk consistency, ModelMaster enamels should be thinned similarly.  For me, the most difficult aspect of airbrushing was geeting a good feel for thinning the paint.  If you're frustrated now, take heart, it will get easier with practice.

About the subject of thinning ratios, over the years, I have noticed so much bottle to bottle variations in paint consistency, that I feel the concept of a paint to thinner ratio is meaningless.  I once had a bottle tha sprayed perfectly with no thinning, however, another bottle of the identical color needed to be thinned.  I've had some bottles in which the paint was very thick and needed a lot of thinner in order to be ready to spray.  So look at you paint and add thinner, a little or a lot, as is needed. 

Also, don't feel that you need to use expensive ModelMaster thinner.  Cheap hardware store mineral spirits work just fine.

Andy 

That's precisely what I mean. At least for acrylics. Get a glass of 2% and see how it flows and drips off a piece of sprue and then get your paint to do the same. Works a charm!

I don't use enamels, but I would imagine it wouldn't be that different.

I am using model masters enamel and tamiya acrylics. Bgrigg I see you are refering to milk so you are tring to say they should be as thin as 2% milk?

I use acrylics, so I use my Mark I eyeball and thin to the consistancy of 2% milk. Except for white and light yellows (ie: not dunklegelb) which I don't thin so much, maybe closer to homo milk.

Depends on what type and brand of paint you are using. We can help you out further with that information.

Andy