Siphon Feed or gravity feed airbrush?

Siphon feed air brushes tend to work best in my experience at 40PSI +/- where as my gravity feeds work best with less.  I usually start with 35 PSI and work from there.  Depending on the paint, you will find that as little as 20 PSI will work OK, but personally myself I like higher pressure for better atomization of the paints. 

The gravity of the situation.

I'll admit to being a noob when it comes to anything technical with airbrushes. I've always used a siphon feed brush. Currently a Paasche H. However, I bought a color cup for it. Does this therefore convert it to a gravity feed because the paint is above the level of the nozzle?

Best not use alcohol with Vallejo

Don't use alcohol to thin the Vallejo paint because it reacts with alcohol and will form lumps (as I later found out). Better is to use Vallejo's own airbrush thinner. Put in about 20% thinner plus a few drops of Golden Arylic retarder.

While thinning is not completely necessary for Vallejo Model Air paints, adding a little thinner plus some retarder helps avoid any clogging problems since Vallejo paint is designed to dry quickly. Also, best is to keep the air pressure under 30 PSI because it can dry the paint before it hits the model, leaving you with a rough, dusty look. For me the Vallejo Model Air sweet spot seems to be about 25 PSI.

Watch the tip of the airbrush for paint buildup and have some Vallejo Airbrush cleaner and a Q-tip handy. If you notice any buildup around the nozzle, just hit the nozzle area with the Q-tip dampened with some airbrush cleaner. Takes just a couple seconds and you should be in business again.

But you're right, Vallejo Model Air is one of the most dummy-proof airbrush paints around. I know of one airbrush trainer who always likes to start his students out spraying Vallejo Model Air because the paint is so forgiving. It sprays well, does a great job of self leveling, and won't cover up details even if you overdo it with too much paint.

Alcohol

Thanks for the tips Joe. I didn't use alcohol to thin the Vallejo paint, I have airbrush thinner for that. I was using it to flush out the brush after years of it sitting, followed by water. I have a couple more projects and will stick with Vallejo until my rusty skills return. Used to be I was pretty good with the airbrush. Hopefully, it's like a bicycle. 

@Greg.........

That's another reason to obtain an Ultrasonic Cleaner, if you don't already have one!  Remember, they work wonders on hard to removed paint jar lids.  180 seconds in the cleaner and shazam.......the top screws right off. 

Peter

Ultrasonic Cleaner

Always thought these were big ticket items, for a decent sized one, they aren't all that expensive. I'll put it on my want list.

 "I didn't use alcohol to

The best thing I've found to clean out dried acrylic paint is an ammonia household cleaning solution. I put a bit in the color cup, spray for a couple of seconds then let it sit for a couple of minutes then flush out with water. If the first time doesn't clear up the spray pattern I'll repeat the ammonia treatment for a few more minutes. Ammonia even removes paint buildup from the exterior if it's wiped on for a couple of minutes. Best to work in a good stream of fresh air to avoid the smell :> ) ......DaveB 

@Greg.........

...............best deal in town is the Harbor Freight ($79) one that for an extra 10 bucks, you get a LIFETIME warrantee*.  It breaks, they give you a new one.  Mine's 3 years old and going strong.  The heater works great and hot liquid cleans better than cold.........

Peter

*I was not able to find this on their website so I would enquire at the store.  It may have been a promotion back when I got it.

Windex for clean up

I agree.  I use Windex cleaner for clean up and thinning (when needed).  I love the Vallejo Air paints

md

Which Windex?

Cheap Vallejo airbrush thinner

Okay, did a lot of research on a good, inexpensive thinner and cleaner for airbrushing Vallejo Model Air / Game Air.

First, neither ammonia-based Windex nor vinegar-based Windex are a good idea as a paint thinner. Both ammonia and vinegar attack the acrylic base in the paint, which can cause it to break down, flake, discolor, or just not be the thin hard finish the paint was designed to deliver.

The thinner Vallejo uses in the Model Air and Game Air lines is propylene glycol, a mild alcohol that's not environmentally hazardous and that has a slight citrus smell. The MSDS sheet on propylene glycol says that it may cause mild skin dryness in some cases and you should avoid getting it in your eyes or drinking it, obviously, but it's pretty innocuous stuff for the most part.

I did find that Armor All Automotive Glass Cleaner, which sells for a few dollars a quart at auto parts stores, has as its prime active ingredient: propylene glycol. BINGO! An inexpensive thinner to use with Vallejo Model and Game Air paints and it's 100% compatible is: Armor All Automotive Glass Cleaner.

I found a 32 oz bottle of the Armor All at Walmart in the automotive section for $2.84 - or 0.3 cents per ml. That contrasts with 8 oz of Vallejo Model Air thinner that I can get on Amazon with free shipping for about $17 - or 8.5 cents per ml. So the Armor All about 28x cheaper!

Good News

Thanks for that Joe, I'm always on the lookout for inexpensive alternatives.

Armor all for cleaning also?

So maybe using armor all to clean an airbrush after use?

Airbrush cleaning

And its available in Canadian

And its available in Canadian Walmart, thanks for the tip but ready for this, at $8.87 per bottle in the Great White North.

Blue Windex with ammonia as valejo thinner/cleaner

I have used the blue stuff with ammonia without incident for 5+ years for not only Valejo but also Polly S.  I have not noticed any degradation.  I now use Valejo Air nearly exclusively so the amount of thinner needed is marginal but with Polly S, which was the paint with which I weathered probably 98% of all my rolling stock, I cut it heavily with blue Windex and have experienced no issue.

YMMV

md

Still cheaper

In Canadian dollars, the Vallejo Airbrush thinner from Amazon Prime will cost $23 for 200 ml, or 11.5 cents per ml. That $8.87 bottle of Armor All is 1.3 cents per ml - so it's almost 10x cheaper.

Windex

My understanding is that the old blue formula with ammonia works best, the ammonia being the main agent for breaking up the polymer/pigment adhesion. I've used it very successfully with Model Master, Poly S, but have not tried it on the Vallejo line

Jor

Straight Ammonia

Couldn't you use straight ammonia?

Using Windex as an acrylic paint thinner

I have no doubt you can get it to work okay, but chemically it's a poor practice, I think.

In checking out various acrylic paint sites, I ran across a manufacturer's site that said using Windex with ammonia was fine for cleaning an airbrush as long as you flush it with pure water last. They also said ammonia attacks the base medium in acrylic paints chemically as well as attacking various plastics and resins (makes them more brittle), so it's a poor practice to use it as a paint thinner for our models.

Since Armor All Auto Glass cleaner uses a base of propylene glycol in it, the same stuff Vallejo uses to thin their Model Air / Game Air line, chemically, you're on a lot safer ground.

"is" versus "may"

Joe, I guess if you replaced "*is* poor practice" with "*may be* a poor practice" I can agree with you. 

Blue Windex with ammonia has worked fine for me and I think there may be a body of evidence amongst the people who use blue Windex that supports it has worked for them as well...or I wouldn't have tried it in the first place. 

I didn't originate the idea just used what had been recommended by others...and for me it also has worked great with no attack of the various rolling stock, or kit plastics, or scratchbuilding styrenes and ABS material that I use, nor a soft finish on any of them, nor paint crazing.  And of course clean up has been a dream.

again YMMV

md

Ammonia chemical warnings

From the Occupational Safety and Health Guidelines for Ammonia:
Liquid ammonia attacks some coatings and some forms of plastic and rubber; this substance should not be allowed to contact copper, brass, bronze, or galvanized steel.

From the guidelines for polycarbonate (plastics) chemical resistance:
Strongly alkaline ammonia materials should be avoided.

Now, it's true the concentration of ammonia is low in blue Windex, so the number of molecules in the paint and plastic being attacked may be small enough that it's generally imperceptible. But chemistry is chemistry - those ammonia molecules are attacking the paint base and model surface mentioned in the warnings, even if ever-so-slightly.

It seems to me if there's an alternative that's now just as readily available, just as affordable, and chemically it's 100% compatible as a thinner, that's the better choice going forward.

I think we are in agreement then...

...it "may" be a poor practice versus alternatives but the concentrations are so low, and the practical evidence such, that we can't say it "is" a poor practice.  At least I wouldn't want to tell the modelers that use blue windex today that they are following "poor practice". 

Once that body of evidence has been built up for Amour All then it can become the gold standard.

md 

Did you say above that you

Did you say above that you were not using Model Air. That means you were using one of their heavier bodied paints such as Model Color, Game Color or similar. If so you should have been thinning at least 20% paint to 80% thinner and whacking the pressure up to 25psi plus. When I use my Iwata Revolution these are the settings I use when spraying these Vallejo paints. It has a .5mm needle. I always use Iwata Acrylic Thinner to thin Vallejo Paint for spraying as it includes retarder which slows ensures the paint lands 'wet'. Iwata Modelair and Tamiya are my go to paints for spraying and have been so for longer than I care to remember when doing Military Modelling which is my other hobby. For these I use finer Iwata Airbrushes such as an Eclipse CS which has a .3mm needle and is my workhorse for most jobs.

Chris