What pressure?

[Robert1968]

When I spray ( when I have a decent compressor ) I would spray Vallejo/ Tamiya / Revell / model air/colour all at around 15psi and I've found when thinning MA/ MC you only need IMHO a couple of drops of thinners and mix very well first. I've always had a few problems with pressure but finding 15psi seems good all round. Never upped the pressure to 40psi unless cleaning the A/b


Hope this helps


Robert

[Guest]

I have a theory! I'm going to put it to the test when I have a spare hour or so. My theory is, that when we select a colour to start a new paint job, we shake the hell out of the bottle, and then make sure there's no gunk residing in the bottom, then shake it again. This process will coat the inside of the dropper nozzle with both paint, and some of the not-quite dissolved residue. Unless the bottle is brand new, this residue will have been lurking there, exposed to what little air there is in the bottle, since we last used it, which will, in most cases be weeks! Now, when we come to squeeze the drops of paint into our airbrush, whats the first stuff to reach the bottom of our paint cup? Yup, the gunk and residue, some of which will almost certainly be part cured.
I just cleaned a nozzle out, from a varnish bottle, (retrieved from the bin, after the last frustrations) and sure enough, there was evidence of thicker varnish, and even some tiny specks of solid material (when I say tiny, I mean tiny, gnat's knacker sized, but plenty enough to trouble a 0.3 nozzle). So, my suggested regime, for those having issues is to:


1, Before shaking the bottle, open it carefully, remove the nozzle, and, with your thumb over the opening, shake the hell out of it.


2. Wash the nozzle thoroughly, really thoroughly and push a wet cocktail stick into the hole.


3. Wipe out the washed nozzle with "Plenty" Kitchen Towel (important that it is this brand, it doesn't leave traces of paper in its path like nearly every other brand).


4. replace nozzle and proceed as normal!


Having done this, I sprayed an old model all over with said varnish, and had no spluttering and no blockage. I did use the 0.4 nozzle/needle combo, but it worked fine, which, for me using Vallejo varnish, was a first.


What a shag, but it makes sense. I will be doing more with other colours...

Ha! That is excellent. The very conclusions I came up with.


I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

[Guest]

Ha! That is excellent. The very conclusions I came up with.
I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

Ha! That is excellent. The very conclusions I came up with.
I made a video describing the problems I encountered, why I think they occurred, and what I did to overcome them.

p.s. Moderator(s) if links to videos aren't allowed, please remove or let me know and I will do it.

Good video Brett, and the expression "great minds think alike" springs to mind! I've been a professional artist and lecturer for longer than I care to remember, and reckon I know a thing or two about paint. This issue has been niggling at me for a while, which made me stop and give some serious thought to what the hell was going on! I knew that there was semi cured paint in the system, from my old silk-screen printing days, when somewhere in the process, you feel the inks beginning to change in their physical state, at which point, you had to stop, clean up and resume, once all was clean, with fresh ink.. What a total shag it was, but I learned a lot about the curing of resins, which, fundamentally we are talking about here. The one reason I never tried the agitator method, is that I used to do a lot of offshore sailing, during which time, I learned that the term "stainless" when used with steel, had to be taken with a huge pinch of salt. Bottom line being that there was no way I was putting anything with Fe atoms in it, in my paint!


Anyway, it's good to see a like-minded soul on the same wave length, and I think we ought to broach this with the rest of the forum.


It must be even worse for you in CA, with the ambient temperatures there, it's bad enough over here in the summer, but I am on an oil paint rendering trip at the moment, so will remain chilled!

[Guest]

As I've said before (usually falling on deaf ears!), most airbrush problems are due to the main variable... the paint!

[Guest]

So true on the "stainless" stuff. I figure that for the amount of time the nut will be in there it should be ok. I don't drop it in until I am ready to use the paint for the first time, and since I generally use mostly the same colors in my chosen modelling subjects, the nut won't be in there long enough to do any damage... I'll use the paint up long before that.


And the ambient temps you speak of are the primary reason I use acrylics in the first place. The temps here range from as much as 110* F in the summer to freezing in the winter. Acrylics and a CO2 cylinder with a regulator allow me to spray inside the comfort of an air conditioned home.

[Guest]

Hi dave does your brush have a pre-set trigger control, if so tighten down on it so the trigger only moves back very slightly and set your compressor down to 12-15 psi. Thin lines requires some control, by moving the brush quite close to the kit and keeping it there, I have just started using Vallejo model air and if you find the paint is slighty thick just add a drop or two of thinner give it a mix and test the brush on some kitchen roll first. if you are able to write your name in thin lines you have everything spot on.


scott

[stona]

The thickness of a line is decided by how far from the object the airbrush is held when spraying. That is fairly self evident. The difficult bit is maintaining the distance to give a consistent line, and also increasing the mount of paint introduced as you move further away (for a thicker line).


There is no avoiding the need for practice. It's something I don't do enough! I've been spraying some dark grey this morning and with this thread in mind I sprayed this on a sheet of white paper (terrible photo!) to use up the paint left in the cup. The thinnest line is a pencil thin line.






It shows a lack of practice, but anyone should be able to do this, or better, with a little practice. Though it won't be relevant to most the paint is a Colourcoat enamel sprayed from an Iwata Eclipse (0.35mm nozzle) at about 35 psi.


Cheers


Steve

[BBdave]

I had a bit of a try this afternoon and turning the pressure upto 30 psi and it sprayed loads better with Vallejo air I just need to refine my trigger technique.


Dave