Thinning Paint

[Ed Gibbons]

Working on the Yankee Hero and using the paint that came with the kit. Been getting brush lines. Paint appears thick. Would thinner help?

 

Thanks. 

[TBlack]

Ed,

What kind of paint are you using?

Tom

[Jaager]

Tracing the kit, I find: Blue Jacket  

The description lists the paint colors supplied.  One of the colors matches True North model paints.

The kit supplies a thinner.  - Were it acrylic - water based, no thinner would need to be supplied - water is commonly obtained.

True North says their product is alkyd.   This is oil based.  I have always had a mental conflict with the term 'enamel paint'.

I have tools and pots that are enamel coated.  Whatever is used to make that coating does not seem to match what a model enamel paint does.

What is seems to mean is that the pigment is suspended in linseed oil ( or similar plant based oil) and an organic solvent.

Reducing the concentration of the linseed oil should reduce the viscosity and allow for a thinner layer more easily spread.  It also reduces the concentration of the pigment, so more layers will be needed o get a desired final density.

 

Use the supplied thinner.  Alkyd lists both alcohol and organic solvents as possible thinners.  The alcohol is probably 95% ethanol (denatured alcohol) ,  the organic could be mineral spirits,  but turpentine works at least as well  or naphtha.  Turp smells better.

[Bob Cleek]

Yes, most paint requires "conditioning" before use. It's generally too thick "right out of the can." Additionally, paints that come as part of an "everything you need to build this kit" package, including paint, notoriously often contain paint that has sat for so long it's become much too thick, if not entirely dried up! The proper solvent will depend on the type of paint. Manufacturers of "model paint" will often have a proprietary thinner, retarder, and accelerator for their products. Check the manufacturer's instructions.

[wefalck]

Enamel as on pots is something different from 'enamels' as in paints ... Enamel as on pots is a layer of glass. It is applied as a layer of a glass-powder mixed with some flux on the bare metal, which is then heated in a furnace to the melting temperature of the glass. A technique thousands of years old. I believe 'enamels' as in paints are named so because they form a hard and smooth layer resembling real enamel. 

[Roger Pellett]

I have experience painting canoes with alkyd resin paints.   Using these paints straight from the can, I had problems with brush marks, and areas where the paint did not cover; effectively a major brush mark.  I was finally able to get a good finish by;

 

Thinning the paint with mineral spirits.  Keep in mind that these are volatile, so the paint will actually thicken while you are painting with the can open.

 

Adding a conditioner called Penetrol.

 

Using a painting procedure called rolling and tipping where the paint is applied with a foam roller and then very gently tipped, or leveled with a paint brush.

 

So is any of this applicable to your situation:

As recommended above, thin your paint with turpentine or mineral spirits. Add thinner if the paint thickens as you paint.

 

Check your brush.  While the roll and tip technique is not going to work for the small surfaces on your model, an overly stiff brush is going to leave marks.

 

Roger

 

[Bob Cleek]

"Rolling and tipping" is for sissies!    Real painters brush or spray. But that's a story for another night. We're not talking about painting acres of topsides here.

 

Seriously, though, the key to a good finish is conditioning the paint. This is much more than just thinning it, although the addition of thinners (paint thinner or turpentine, acetone, etc.) can go a long way to improving consistency of what comes out of the can. Proper conditioning is dictated by interrelated environmental variables such as temperature and humidity. Perhaps the most important consideration is the speed of drying. If the paint dries too fast, brush strokes (and roller stipple) will not have time to "lay down" sufficiently and yield a uniform thickness on the painted surface and "maintaining a wet edge" will consequentially be much more difficult, leading to even more dried brush strokes on the dried surface. Penetrol (which is now difficult to source in environmentally "woke" jurisdictions that have outlawed it due to its VOC content,) is basically raw linseed oil. (Not "boiled" linseed oil, which isn't boiled at all, but rather contains added heavy metal driers that accelerate the polymerization of the oil binder in the paint, causing it to "dry" faster. A dried coat of paint is simply pigment bound by polymerized oil following the evaporation of the solvent thinners.) Along with the temperature of paint when applied to the surface, the proportion of driers to oil in the applied paint dictates how fast it "dries" and a greater proportion of oil to driers increases the drying time and, thus permits brush strokes to "level" and disappear. Ideally, the object of conditioning is to yield paint that levels adequately before drying and dries as soon after leveling as possible. Many manufacturers of modeling paint offer proprietary "retarders" that slow their paints' drying time, "accelerators" that speed it up, and "thinners" that thin their paint. If that's true in your case, use the paint manufacturer's proprietary conditioning products and follow their product instructions for best results.

 

Thinners (volatile solvents that thin the oil,) on the other hand, primarily regulate the viscosity of the paint, making it easier to spread. Over-thinning, however, will reduce the gloss of the coating (not a problem with models so much) and dilute the pigment load of the paint, thereby reducing its ability to "cover" differing underlying colors (which can be a problem in modeling.) Moreover, the volatility of solvents varies. "Hot" solvents are more volatile and evaporate quickly, such as acetone, while other solvents are less volatile and evaporate less quickly, such as mineral spirits. (And one must beware of modern "green" and "ordor-free" substitute thinners which may be incompatible with some oil-based enamels! Just because they may work for cleaning brushes doesn't mean they will work for thinning paint properly. Testing is always advisable before diving into painting the workpiece.)

 

Conditioning paint is one of those things that's easy to teach by the "show and tell" method, but not so easy to teach with written instructions. It's not  all that complicated, though. It's like baking a cake. A half hour of instruction by a knowledgeable  painter would be time well spent for anybody who wants to achieve good painted finishes, particularly with oil-based enamels.

 

While a good brush is a joy to use, (and remember: natural bristles are for oil-based paints, synthetic bristles are for water-based paints) a poor finish is far more often the fault of the paint and the painter than it is the fault of the brush. Within reasonable limits, it's generally more the skill of the craftsman rather than the quality of his tools that determines the quality of the finished product.

 

Multiple thin coats produce the best finishes. Don't expect to get the perfect finish with a single finish coat. Generally, a properly prepared (smooth) and primed and base-coated surface will require a minimum of three rather thin finish coats to "cover" sufficiently. Sand those brush strokes "smooth as a baby's bottom" and give it another coat. Repeat until perfect.  

[glbarlow]

OR…you could toss the likely very old paint that came with the kit and replace it with water based acrylic available from any number of places and choose your own color combinations. 

[Ed Gibbons]

20 hours ago, glbarlow said:

OR…you could toss the likely very old paint that came with the kit and replace it with water based acrylic available from any number of places and choose your own color combinations. 

Do you find the acrylics are better to work with? I also do woodworking and I have slowly moved to water based stains and topcoats. I’m currently using the paint that came with the kit. 

[glbarlow]

I haven’t used enamel oil based paint in over a decade. Water based acrylics are far far easier to work with in multiple ways. I’d dump the old paint and get acrylics. I doubt you’d find few on MSW that would disagree.  

[Ed Gibbons]

30 minutes ago, glbarlow said:

I haven’t used enamel oil based paint in over a decade. Water based acrylics are far far easier to work with in multiple ways. I’d dump the old paint and get acrylics. I doubt you’d find few on MSW that would disagree.  

Do you spray or use a brush?

[glbarlow]

Strictly brush, I enjoy painting. 
 

 

[PRS]

I use acrylics all the time and Vallejo are great for brush painting and ready available. They are good for airbrushing but you are limited to what thinner you can use. The acrylic thinner by Tamiya and Vallejo's own thinner are the only two I find work good.

 

Now cleaning the airbrush of just brushes is harder with Vallejo as it seems the pigment is so fine it gets everywhere. To clean my airbrush I have to use lacquer thinner and always remove the needle as it gets all over.

 

For strictly airbrush painting the Tamiya acrylics work better but they do not brush paint as well. Tamiya acrylics have an advantage they they will take just about anything as a thinner and you can use lacquer thinner for them if you want to but the smell is pretty intense. They do clean up easier in the airbrush though.

[bartley]

Yes Paul, I am a great fan of Vallejo paints as well.  A good range of colours and, as you say,  excellent brushing characteristics,  I spray them when I can.  As you know there "Game Air" range is designed for spraying but I mostly use the "Model Color" range.  For brushing I dilute them by about 50% with their thinner and apply several coats. It is then hard to tell the difference between brushed and sprayed in my opinion.

 

John

[Phil Babb]

If your using a spirit based paint ,easy to tell by a good sniff, use pure gum turpentine to thin. not white spirit, it stops the feather edge you get with white spirit or turps.

[Bob Cleek]

Some use either high quality oil or acrylic tubed artist's paints, conditioning these for brush or airbrush application. These are far less expensive in the long run and generally don't dry up. You do have to sometimes mix your own colors, of course. Many prefer pre-mixed bottled colors, of course.