Another few details where I am unclear. All comments will be appreciated. I will use the case of some cabooses I am about to do. I will be using Model Master Acryl from primer to color to clear gloss (for decals) to final clear flat.
a) After the primer, how long to wait (or how to tell) until color coat?
b) After the 1st color coat, how long until the next? (Armor yellow over white primer will take several, especially as I'm learning not to apply thick coats.)
c) After the color coats, how long until the clear gloss for decals?
d) After the decals are dry and washed (after setting solutions), how long before final clear flat coat(s)?
I've probably missed these details in several threads I've scanned, so I will appreciate any clarification. If it is important, I am in central Texas and humidity is seldom high here. I imagine it can vary with paint types, but I'm trying to develop acrylics as my base case.
Paul
Modeling HO with a transition era UP bent
Hi Paul. I've airbrushed many items using these paints, but in (muggy) Eastern Canada. As a general rule you want each type of paint to dry fully before going to the next. In other words, wait for the primer coat to be completely dry before going to the color coat, and wait for the color coat to be completely dry before going to the clear coat, etc. For enamel, I use the "sniff" test to make sure the piece is completely dry. Here in Canada, it can take up to 3 days. For acrylics, there is no similar test and I suspect that 24 hours will be sufficient in your neck of the woods. 48 should be more than enough. Now when you are applying a single type of paint (e.g., yellow coat), you can apply several coats within the same session - just make sure thet item is not "wet" between single coats. I use a fan to speed things up - making sure there is no dust around.
By the way, acrylics dry fast, including on the nozzle of the airbrush, so it's a good idea to clean the nozzle between coats during a single session. I keep a second airbrush bottle filled with distilled water for this purpose. Just change the bottle and clear the path of the airbursh with the water, using a rag to catch the fluid. Putting a rag on the nozzle with create a pressure in the other direction (you will hear the bubbles) - will help clear the path as well.
Simon
a,c,d at least 24 hours.
Applying addition color coats (same color), I will use a hair dryer and then keep painting. Then I will let it dry at least 24.
Henry
COB Potomac & Northern
Shenandoah Valley
Thanks, guys. I needed a starting point as I knew the curing issue is important to avoid novice mistakes but I can't remember what I read or where. I did watch a nice YouTube video where the guy demonstrated painting a part with primer (I don't think he mentioned the time gap), but then applied 2 color coats, commenting "back in an hour" after the first. I got a lot from that video, noting that light paint application for each coat is important (I was blasting in first attempts).
snjroyBy the way, acrylics dry fast, including on the nozzle of the airbrush, so it's a good idea to clean the nozzle between coats during a single session. I keep a second airbrush bottle filled with distilled water for this purpose. Just change the bottle and clear the path of the airbursh with the water, using a rag to catch the fluid. Putting a rag on the nozzle with create a pressure in the other direction (you will hear the bubbles) - will help clear the path as well.
I am still quite puzzled on the cleaning issue with the (MM, my case) acrylics. I acquired a jar to flush into, which I'm sure will help. My practice has been to wrap up by spraying denatured alcohol (from the cup or a siphon paint jar), which will now nicely go into the flush jar. Then I take the airbrush to the sink and clean in hot, soapy water.
What I don't "get" is that several folks say they just flush their airbrush with thinner, cleaner, Windex, etc. and then use it next time. In my case, the tip has a little paint on its exterior (easy to clean) as well some buildup inside the tip guard / nozzle extension. The nozzle cylinder has quickly dried paint inside and takes awhile to clean that in soapy hot water, using a pipe cleaner, not easy or quick. It seems to help to dip the pipe cleaner in alcohol. So, basically, I'm doing a complete cleaning with each step of using the airbrush.
I'm wondering if I can do better. I don't mind a complete cleaning with each use but would like it to be more efficient, particularly for cleaning the shiny paint cup and the tip nozzle inside surface, which take the most time. Should I do my ending flush with Windex instead of denatured alcohol? I also have (Medea/Iwata) Airbrush Cleaner, that I have not tried yet, which the guy in the video used (diluted 50%). And should I immediately remove the tip, it's protector extension and the cup and drop them into xyz solvent immediately (before cleaning) to make final cleaning, a few minutes later, easier? Etc.
Any additional comments to help me up the learning curve are most welcome.
For cleaning, I take the airbrush apart and clean it with Windex. I bought a set of wire brushes to clean the tubing. I only use acrylics and I have very few stains on my 40 year old Badger...
As far as time, if it's a acrylic primer, and an acrylic color, if no masking is involved, you can spray just as soon as the primer is dry.
I always wait until there is zero smell before decal work. This time can be as little as 2-3 hours, to as much as 24-36 hours, depending on temperature and humidity levels.
For gloss/flat clear coats, again, I use acrylic, so as soon as the prior work is completed and dry.
On airbrush cleaning, I run distilled water through the airbrush, then disassemble it and wipe it down with a soapy rag, and rinse and air dry once I am finished spraying. When changing colors, I spray the distilled water, or a acrylic airbrush cleaner when I have it, only until the airbrush sprays clear.
I don't have a single stain or paint build up section on my airbrush from this method.
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
If You find Lacquer thinner offensive, then this advice won't be good for You.......I have been pro-painting full size trucks/cars since the early 60's, air brushing since the 70's. In that time and to this day, I use Automotive General purpose lacquer thinner to clean My guns and air brushes, no matter what kind of paint I am using. When I finish painting.....the color that I used has it's own bottle with lacquer thinner inside. I put the cap on the paint bottle and screw the tip and lid on the lacquer thinner bottle and shoot full spray out the nozzle and then back flush for a few seconds, (that's done by holding a paper towel over the tip) until bubbles form in the bottle, wipe the tip clean and Your done. I do that every time I use the air brush........no matter what kind of paint I used. I have a tip for every kind of paint/color and it's own cleaning 1and3 oz bottle. For the price of a complete set of bottle, lid, gasket, and tip, it is worth it to Me and I never have to go through all that dissasembling bs to clean the brush. I use Paasche H/VL brushes from the 80's era and they are still like brand new........
Take Care!
Frank
Thanks again, all.
Frank, that blue truck is just amazing! Must be a real one photoshopped. You can't fool us!
Paul,
No I'm not fooling anyone..LOL....It's a 1/14 scale RC Truck kit By Tamiya. I originally built it for My youngest Son in 1994. He asked Me if I would redo it for his Son, about two yrs. ago.........I'm standing behind it, in the next pic'......It's on My picnic table in My yard:
A Looot of stuff.......goes in that truck......LOL!
Good luck with You're painting........most important point in all......be patient!!!
Give paint some time to cure, not only dry, when changing colors. I always double what they say on instructions.
I would lean towards the faster times with acrylics. I've put a black plastic freight car on a painting handle and sprayed it with gray primer, come back an hour later and sprayed it with boxcar red, and an hour later sprayed it with gloss acrylic (for decals). Worked fine, but I do usually allow the gloss to dry overnight before decalling just to be sure. If I'm going to mask the paint for a second color, I'd usually leave it overnight also.
peahrensIn my case, the tip has a little paint on its exterior (easy to clean) as well some buildup inside the tip guard / nozzle extension. The nozzle cylinder has quickly dried paint inside and takes awhile to clean that in soapy hot water, using a pipe cleaner, not easy or quick
I take the protective tip and put it in a little jar of alcohol and clean it with a Q-tip or a toothpick, after it soaks a while. There is a painter on the Brasstrains.com videos and he dumps his paint cups in a jar of laquer thinner. He has multiple cups.
The ammonium in Windex can damage metal over time, so if you clean with that, flush it well.
In normally mobile room air at about 60% ambient relative humidity, the thin coats one typically makes of any kind of paint using an air brush using acrylic paints should dry literally within minutes. I don't mean you can then touch your finger to it to see, but certainly within about 20 minutes you should be able to add a topcoat of whatever you need to use. For more patient people who like heavier insurance, wait a full hour.
If you have every wiped a countertop in your kitchen and looked at the reflection to see how well you have done, at a low angle, you'll see plenty of streaks of water. Come back in 20 minutes and see how much of it is left in the conditions I specified above. That's a lot of water evaporated. Comparatively, you are placing a tenth of that in the same surface area.
I won't claim that the paint has 'set up' enough to stay in its place....that part of the chemistry is beyond me, even as epoxies need setting up. That's why you shouldn't touch it to see. But for the purposes of applying a topcoat, a full hour in average temps/humidity/room air movement should be very reasonable.
The Testors website indicates 24 hours for a full cure for its Model Master acrylic paint.
Thanks for all the pointers, all. I'm actually making progress.
On the drying issue, I see what you mean about added color coats, as my UP cabooses are taking a number of armour yellow coats over white primer. I am trying hard not to apply coats that are heary. Today I added a couple of coats after waiting perhaps 40 minutes.
I'm equally enthused about progress on cleaning the airbrush. I used Model Master primer but am using ModelFlex color coats. I especially had issues with fairly hardened primer on the color cup and the tip guard, when I had sprayed with some denatured alcohol to preliminarily flush the gun for final cleaning. As I described earlier, it was tough to then get the stainless color cup clean, as well as the tip guard, using soapy water and alcohol.
Today I tried a new approach, with some definite success. When done painting (ModelFlex) I added some Windex to the color cup a couple of times and sprayed into the waste receiver. I then had 2 paint suction bottles ready, both filled with Windex. (I removed the color cup and tossed it into a small jar with Windex).
I sprayed from the 1st bottle into the waste receiver, backflushed it a bit and sprayed a bit more. So this becomes the "dirty" Windex suction bottle. I then sprayed from the 2nd (clean Windex) bottle without backflushing, to keep that Windex clean. I then tossed the cylindrical tip guard into the Windex jar with the color cup and headed to the sink.
At the sink, I disassembled the airbrush further and quickly cleaned everything easily with soapy water, Windex and pipe cleaner and tooth brush. The formerly quite tough to clean color cup and tip guard cleaned in seconds. The tip cleans easily as well. When completed, I sprayed some distilled water through the brush, though I have read elsewhere that just cleaning with Windex is ok, versus leaving the brush soaking in it for long periods.
I don't know for sure if it will work this easily with the Model Master primer or colors but I suspect it will be comparable.
If using solvent based paints, which I plan to minimize or avoid, I may need to change from Windex to something stronger.
Between proper painting techniques, proper paint booth exhaust and effective airbrush cleaning, there is a definite learning curve, at least for me.
Thanks again for all input received on my various threads.