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Acrylic Paint Education

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Acrylic Paint Education
Posted by ndbprr on Monday, November 21, 2022 7:43 AM

I have finaly used up my Floquil paints and diosol. So now I have no choice but to switch to Acrylic. I use a Pasche double action air brush.  What is the ratio of paint to thinner?  What is the best thinner?  How durable are acrylics? How many coats for coverage? anything else I need to know to not reinvent the wheel?

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Posted by NVSRR on Monday, November 21, 2022 10:30 AM

since They all vary,  consistency of milk is a good place to start   Thinners usually water or some use alcohol.   Number of coats depends on color.  

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Posted by wjstix on Monday, November 21, 2022 10:48 AM

Acrylics are very durable, and do a good job of covering so in most situations only one coat is required. Two light coats might be needed for a light color (yellow for example).

One thing to be aware of is acrylic paint dries much quicker than solvent based paint. In some ways that's good - you can spray a primer coat and then spray the next color over it in only an hour or two. However, it also means that as soon as you finish spraying, you should immediately clean out the insides of your airbrush. Otherwise, you may find the insides completely blocked with dried, gummy paint.

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Posted by trainnut1250 on Monday, November 21, 2022 11:25 AM

I would look up the MRH e book on acrylics. It will answer most of your questions. Acrylics are a different animal than solvent based paints. There is also Scale Coat, Star and Trucolor paints that are still solvent based.

I use a single action, external mix brush to avoid (mostly ) clogging issues....

 

Guy

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Posted by dti406 on Monday, November 21, 2022 2:31 PM

ndbprr

I have finaly used up my Floquil paints and diosol. So now I have no choice but to switch to Acrylic. I use a Pasche double action air brush.  What is the ratio of paint to thinner?  What is the best thinner?  How durable are acrylics? How many coats for coverage? anything else I need to know to not reinvent the wheel?

 

Why acrylics? I use Scalecoat for most of my painting except where some of my leftover Floquil gets used. 

Scalecoat does not need a primer and covers well with one coat and leaves a shiny surface for decaling. 

Rick Jesionowski 

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Posted by snjroy on Monday, November 21, 2022 7:17 PM

Hi there. You can thin with distilled water. And yes, it dries fast. After a few passes, I let the film dry to the touch and apply more. Thin coats will avoid runs. Using a fan helps to speed up the drying. While it dries between coats, I flush my airbrush using a second bottle filled with distilled water (just press the trigger with the nozzle against a rag). Works very well. Yes, milk is about right in terms of consistency. I always test my mix against a piece of wood. If too thick, I add the water, or the opposite.

Simon

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Posted by PennCentral99 on Monday, November 21, 2022 8:40 PM

I found this on the internet some time ago, I have not tried all; but, for the most part, the ratios and pressures seemed to be good starting points.

Hobby Paint
Paint 
Thinner
Ratio
Pressure
Clean-Up
Polly Scale
Distilled Water
3:1 or 4:1
15-25
H2O/Washer Fluid
Floquil
Solvent/Thinner
2:1 or 3:1
12-20
Lacquer Thinner
Badger Modelflex
Water Very little, if any
 
25-30
H2O/Washer Fluid
Tamiya
Alcohol
2:1
15-20
H2O/Washer Fluid
Vallejo Model Color
Vallejo Thinner
3:1
20-25
Lacquer Thinner
Vallejo Model Air
Vallejo Thinner Very little, if any
 
20-25
Lacquer Thinner
MicroLux
Vallejo Thinner Very little, if any
 
20-25
Lacquer Thinner
Humbrol

Water
1:1 or 2:1
15-20
Water
Gunze Sangyo
Alcohol or
Distilled Water
1:1 or 2:1
20
Water/Alcohol
Scalecoat II
Solvent/Thinner
1:1
15-20
Lacquer Thinner
Model Master (Testors)
Universal Thinner Very little, if any
 
18-20
H2O/Washer Fluid
Future
Alclad II
Lacquer Thinner    Very little, if any
 
12-15
Lacquer Thinner
Pactra
Lacquer Thinner
1:1
20-25
Lacquer Thinner
Pactra Acrylic
None
 
25-30
H2O/Washer Fluid
Lifecolor Acrylic
Distilled Water, Washer Fluid
1:1
12-15
H2O/Washer Fluid
Craft Store Acrylics
25% Liquitex Slow-Dri, 25% Flow Improver, 50% water
1:2
20-30
 

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Posted by SeeYou190 on Monday, November 21, 2022 11:13 PM

dti406
Why acrylics? I use Scalecoat for most of my painting except where some of my leftover Floquil gets used. 

Same here.

-Kevin

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Posted by ricktrains4824 on Tuesday, November 22, 2022 11:20 AM

Different brands need different thinners.

Acrylics do require more "oomph" to spray, no matter what brand, so the 15-20psi used with Floquil will not work at all with acrylics. I've found 35psi a good "start point" and adjust from there.

I reccommend proper ventilation and PPE when airbrushing with anything, but will note it especially required on a couple.

TruColor paints - (technically acrylic, but use acetone for cleanup.) These have become my go-to of late. Sprays nice and smooth, and only need primer if you are spraying over a darker colored car. (Like the old Black styrene MDC/BB kit cars, or "boxcar brown" molded Accurail cars.)

For this paint, proper ventilation and PPE required.

They have their own thinner mixture, which I very rarely need to use. (I've had to use it twice in 18 months, though I don't paint every week.) They also have TCP-999 Rejuvinator, for rescue of old bottles that have started to have the thinner flash off. 

Note: Do not let TruColor paints freeze. They really, really dislike cold. (I do not order paint from late October through early April via mail.)

My other paints are:

ModelFlex - (their formula recently changed, and not for the better imo) - I have never needed to thin, and clean up is with window washer fluid. (Their new bottles I can not get to spray smoothly, no matter how I prep the model.)

Modelers Decals & Paint (Kalbach Hobby Store) - This sprays smoothly, is thinned with very little isopropyl if needed, cleans with either isopropyl or window washer fluid. 

For this paint, proper ventilation and PPE required.

Valejo - Acrylics in the "air" line don't need thinned, I again use window washer fluid for cleanup. Non-air line I thin with Golden Airbrush Medium, cleanup is still window washer fluid. Their acylic primer seems to stick to anything, and rarely needs thinned.

Tamiya - I've only tried airbrushing with Tamiya once, thinned with isopropyl alcohol, and cleaned with isopropyl alcohol. I do like their rattlecan primer for quick "don't feel like using an airbrush" jobs.

For this paint, proper ventilation and PPE required.

Craft store acrylics - I use a mix of browns and oxides for weathing of trucks and wheelsets, thinned heavily with a mix of the aforementioned Golden Airbrush Medium, and distilled water with flow-aid added in. (3:1, 4:1, or higher thinner to paint, depending on how thick the craft paint is. I usually have 4:1 ratio of medium to water.) The craft acrylics work well for this, because they dry dead flat.

 

Cleanup is soapy water or window washer fluid for the craft store acrylics, if I'm only doing the craft stuff, I take a ice cream bucket (after I've eaten the ice cream) half full of soapy water, wipe out the airbrush with a damp paper towel, then stick it into the soapy water and spray it right inside the bucket. If I've done other painting, I already have the window washer fluid there, so I just use that.

I don't record the exact mix of colors on the craft paints I use, just grab a few different browns and a oxide or two for when I need to make a batch, and mix to an "looks good" dirty color. (This allows slightly different dirty rusty coloration for cars from "elsewhere".) I do crank up the pressure here, to roughly 60psi, for a more "splattered on dirt" look. (Note: This makes it dry extremely fast. So be ready to clean as soon as you are done spraying.)

Ricky W.

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Posted by Lee 1234 on Tuesday, November 22, 2022 11:56 AM

Check your needle and see how many grooves are in it on the back.  The 3 groove (VLN-3) will spray acrylics best.  You need to change the aircap and tip to match the needle.  Paasche recommends 30 to 35 lbs pressure depending on what you are spraying.  

Lee

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Posted by ricktrains4824 on Tuesday, November 22, 2022 2:53 PM

Lee 1234

Check your needle and see how many grooves are in it on the back.  The 3 groove (VLN-3) will spray acrylics best.  You need to change the aircap and tip to match the needle.  Paasche recommends 30 to 35 lbs pressure depending on what you are spraying.  

 

Iwata needles are smooth. So that grooved end must be a Paasche thing.

Ricky W.

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1: It's my railroad, my rules.

2: It's for having fun and enjoyment.

3: Any objections, consult above rules.

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Posted by JDVass on Wednesday, November 23, 2022 7:14 PM

For acrylic paints I have had really good results with the following recipe for thinner.

1/2 Cup  or 4oz Distilled Water
1/4 Cup or 2oz  Isopropyl Alcohol 91 or 99%
10 ml  Flow Improver
1ml Retarder
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Posted by kasskaboose on Thursday, November 24, 2022 11:06 AM

I've never had luck with only using one coat of paint--regardless of type.  No worries since it prevents the plastic from showing through the paint.  I also don't purposely paint a heavy coat knowing a second is needed.

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Posted by ricktrains4824 on Thursday, November 24, 2022 5:39 PM

None of my projects is ever just one coat of paint, but are all done with multiple light coats, deliberately done that way to allow fine details to still show, and have no runs. 

Last railcar I painted was at least a minimum of 6 different coats, although from Different spray angles, to catch all areas. But those light coats, at different spray angles, still allow details like rivets, etc... to show, just as painted the correct color.

I could lay down a thicker coat to do things in one coat, but then that risks flooding details, and runs/drips.

Ricky W.

HO scale Proto-freelancer.

My Railroad rules:

1: It's my railroad, my rules.

2: It's for having fun and enjoyment.

3: Any objections, consult above rules.

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