Acrylic thinner problems

[CasualModel98]

I tried to make my own acrylic thinner using 50% water and 50% denatured alcohol (ethyl and methyl alcohol). I did not add any acrylic retarder or flow improver. Just testing out this concoction.

I mixed this 50:50 with Tamiya acrylic paint.  However after spraying, I find that the paint becomes powdery such that it rubs off just from touch. Just rubbing my fingers over the painted surface would make the paint come off as powder.

Did I dilute it too much such that the bonding agent is too weak? Or did the alcohol destroy the bonding agent that makes the powder stick to the body as paint?

Or did I add too much water since the mixture is effectively about 50% paint, 25% water and 25% alcohol.

 

 

 

[John Laidlaw]

It's the alcohol that's breaking down the paint as it's chemically incompatible - replace it with 70% isopropyl alcohol, and ensure you use distilled water. I'd recommend adding a retarder and flow improver when you're happy your mix is working, as they will eliminate or at least severely reduce tip-drying on your airbrush.

 

HTH

[CasualModel98]

Wouldn't IPA cause the same problem as its also an alcohol? Or I need to reduce the alc concentration?

[cruiserguy]

Hi CM98

 

Not really, as I am sure Tamiya thinners contains IPA. So John's suggestion is a sound one.

 

Best Wishes,

 

Will.

[Beardie]

It sounds like you have simply made the acrylic polymer too thin by dilution. Commercial acrylic thinners contain liquid acrylic as the paint film will become too weak if you thin it too much with plain water or alcohol.

[John Laidlaw]

8 hours ago, CasualModel98 said:

Wouldn't IPA cause the same problem as its also an alcohol? Or I need to reduce the alc concentration?

 

No. IPA is the chemically correct alcohol. Methylated spirits is completely different, and is the root of your problem.

 

Certainly play around with dilution ratios after that to find what works for you.

[BrianI]

For distilled water, could the water from the water tank from a condenser tumble dryer do?

[John Laidlaw]

3 minutes ago, BrianI said:

For distilled water, could the water from the water tank from a condenser tumble dryer do?

 

I suppose it could . I can't guarantee how clean it would be, or whether the distillation had removed all of the impurities, but it might be better than tap water.

[BrianI]

14 hours ago, CasualModel98 said:

I tried to make my own acrylic thinner using 50% water and 50% denatured alcohol (ethyl and methyl alcohol). I did not add any acrylic retarder or flow improver. Just testing out this concoction.

I mixed this 50:50 with Tamiya acrylic paint.  However after spraying, I find that the paint becomes powdery such that it rubs off just from touch. Just rubbing my fingers over the painted surface would make the paint come off as powder.

Did I dilute it too much such that the bonding agent is too weak? Or did the alcohol destroy the bonding agent that makes the powder stick to the body as paint?

Or did I add too much water since the mixture is effectively about 50% paint, 25% water and 25% alcohol.

 

 

 

What air pressure were you spraying at, and how far from the model? Too high a pressure and too far a distance can result in the paint drying in the air, so landing on the model as a dry powder. 

This "recipe" might be worth a try?  http://scalemodellinginfo.com/make-your-own-acrylic-thinner/

[LaurieS]

I would not mess about with alcohol IPA etc. They are better used for cleaning bits and pieces.

 

My advice is to use the paint manufacturers thinners. It is properly constituted with driers and

all the other things. Good thinners usually are the basis of the paint. This enables thinning to

be made without wrecking the integrity of the paint ie stickability and flattening out plus not

drying out as it leaves the airbrush and before hitting the plastic. IPA will dry in the air fast.

 

It is not a good thing to use water as a thinners. Its molecular system is such that it sticks together.

Put a blob on the work top and the surface tension holds it together with rounded edges. Put a

blob of good thinners in the same way and it will flatten out which is what is necessary in a good

paint system. After it has dried you can see the evaporated sticky bit of the paint.

 

Laurie

Edited December 1, 2016 by LaurieS
For got capital to start a sentence, what a goon.

[John Laidlaw]

From the MSDS sheet for Tamiya's X-20A thinners:

 

Water 54.9175%
(Purified water)
Butan-1-ol 19.9700%
(Secondary Butanol)
Propan-1-ol 14.9775%
(Normal propyl alcohol)
3-methyl-3-methoxy butan-1-ol 9.9850%
(3-methyl-3-methoxy butanol)
Additives - unknown 0.1500%
(Maybe several surfactants)
TOTAL 100.000%
 

Nearly 55% water, nearly 30% of two forms of butanol, nearly 15% propylene alcohol (which tends to be the one you smell when you open the bottle), and "additives", which are most likely there as flow improvers, retarders , and surfactants (reducing surface tension of the water).

 

When I'm not using Tamiya's lacquer thinner, or Mr. Color Leveling Thinner, I use my own version of a recipe of acrylic thinners, very similar to the one posted earlier by Brianl. I use 70% IPA as it's easier to get hold of, but up the ratio to 60%. Dead easy to mix (it really isn't rocket science), works every bit as well as X-20A, and works out to a tiny fraction of the cost per ml.

[Steve Noble]

From a personal point of view I never stray from the manufacturers own brand thinner. It's been designed from the start to thin their paints, so you know it's compatible and won't give you any surprises and ruin your paint job. Trying to brew your own mix is all well and good if  it actually works correctly. What you actually save in money terms is pence per paint job. So I don't bother to skimp on proper thinner. For clean-up sure, I'll use cheap gun cleaning thinner for flushing the airbrush after use, but never for thinning the paints.

[LaurieS]

5 hours ago, Steve Noble said:

From a personal point of view I never stray from the manufacturers own brand thinner. It's been designed from the start to thin their paints, so you know it's compatible and won't give you any surprises and ruin your paint job. Trying to brew your own mix is all well and good if  it actually works correctly. What you actually save in money terms is pence per paint job. So I don't bother to skimp on proper thinner. For clean-up sure, I'll use cheap gun cleaning thinner for flushing the airbrush after use, but never for thinning the paints.

 

Steve my own thoughts entirely one 110%.

 

Takes a long time to construct a model. Why chance messing it up.

 

Laurie

 

[Steve Noble]

23 hours ago, LaurieS said:

 

Steve my own thoughts entirely one 110%.

 

Takes a long time to construct a model. Why chance messing it up.

 

Laurie

 

Exactly. No point messing up your work. I usually buy a large bottle of thinner of the correct type for the paint I'm using, then I only thin the paints with this and find it lasts for a long time. I'd never use the expensive stuff for flushing the airbrush out, only cheap stuff for that. The proper thinner is way too expensive for cleaning with.