I am not a painter by any stretch of the imagination. I am interested in doing a few things myself. Probably a receiver set (maybe 2) and a couple slides in the next couple months and maybe a complete 1911 somewhere down the road.

I have a question about sequence. If gas out indicates oil and then it is cleaned again, why the additional step of blasting again? What makes the initial blasting no longer acceptable for surface preparation?

Why isn't boiling water added to the cleaning options? Is there some reason that boiling water will have a detrimental effect on bare metal especially for small parts including handgun slides?

What have you used for a sprayer? Anyone use an airbrush? Which make and model and how was it set up? Needles, etc?

Any advice, points, comments or cautions will be appreciated.

Not sure why anyone would media blast twice. You degrease first so it does not contaminate the media. You don't use water because it will flash rust fast. Break clean works best for me and evaporates fast. I myself degrease, media blast then degrease again. You don't want to use an air brush normally but could if wanted. I have an iwata and sata detail gun that work better than anything I could imagine. I have air brushes as well but would never use them for that.

So, in your view, a detail gun is the right size tool? Needle size? My question on the boiling water was more thinking of aluminum and stainless. I guess I could see some corrosion or a film developing from water use. Yeh, my barroom logic on it had me degreasing, media blast, gas out and a final step of degrease. I didn't see the purpose of blasting again even If it failed gas out. But, there it was right in the training video.

It is. I used sata from other work and it was perfect then bought the Lph 80 with .8 tip and it's been great. I'm on my second one in about 5 years. The method/setup really changes with color, for example tungsten is course and thick while sniper grey is thin and fine but hardener ratio stays the same. Like any other painting, the prep is the main part.

Been doing refinishing for over a dozen years.  

Iwata LPH-80.  0.8 tip.  Happens to be what NIC Industries uses when they Cerakote (they make the stuff).  We had already been using that gun before we went out to get Certified and were pleasantly surprised to see that's the gun they use.

Degrease for us is with Acetone.  We soak it.  After gas out, you will often see a discoloration of the metal.  It's potentially a form of oxidation or a very slight residue from oils coming to the surface and evaporating, but leaving a little behind in the roughed up surface, so we re-blast everything after gas out.  Prep really IS the most important part of it, and a re-blast typically only takes a couple of minutes and it's a little more insurance.  YMMV.  Have fun!

Got it. Now the whole reason makes some sense. The oil, or whatever is present or shows itself during gas out "could" have a deleterious effect on the completed blasting surface prep.

Thanks, that has been bugging me for days trying to see the rhyme or reason of it.