My AB gummed up something awful; Model Air and Model Colour paint

[Stevekir]

I've been practicing airbrushing on several pieces of gash model parts, successfully using Vallejo "Acrylic Polyurethane Surface Primer 73.601", Xtracrylx paint thinned 2/1 paint/thinner with Xtracrylx "Thinners". OK. But I then used Vallejo "Model Color 70.953 Flat Yellow" thinned. The AB gummed up after about 20 secs. I noticed that the paint in the cup had coagulated and was difficult to remove so I did a full clean (needle out, the three nozzle bits out). When returning the needle to its full forward position I noticed a yellow worm coming out of the nozzle. So I cleaned again, this time using one of those long thin AB cleaners.

== So what caused the problem? (Could it be that Xtracrylx Thinners and Model Color paints are incompatible?)

== If not, what happened? If yes, is there a thinner usable with both Vallejo Model Air and Model Color paints?

== Should I use one of John's Vallejo thinners:

"30ml Thinners (New Formula) Vallejo Model AIR 71.061", (or is "Model Air" different from "Model Color", thinners-wise), at:

Acrylic Paint Thinners for Model Paints

or

"17 ml Thinner (200), Vallejo 70.524" (which does not mention "Model Color" or "Model Air", at:

ScaleModelShop

== Also, despite thorough searching, I cannot find a clear explanation anywhere for the difference, concerning model aviation airbrushing, between Vallejo Model Air and Vallejo Model Color? Which is best, what's the difference in use?

Can anyone help please?

Thanks.

 

[stona]

Sounds like the Xtracrylics thinner doesn't agree with Vallejo paints. I've had Xtracrylix turn to custard when inadvertantly exposed to cellulose thinners so something similar may be happening with the Vallejo.

I'd always suggest using own brand thinners unless you are confident to use your own,be that isopropyl alcohol or water with added drying retardant.

Vallejo Modelair is prethinned and supposedly airbrush ready. Vallejo Modelcolor is not.

Hopefully Laurie will be along soon as he has a lot of experience with Vallejo paints.

Cheers

Steve

 

[Stevekir]

Well, that reply itself has taken me forward quite a bit. Thanks.

 

[Ian M]

Not that this helps your situation but Vallejo thinners work really well with Xtracrylix paints.

Model Air is ready for use. If you want it a bit thinner, a drop of distilled water does the trick. Just don't use to much or the paint will split out.

IanM

 

[tecdes]

Thanks Steve (Stona) must get a tee shirt with Vallejo on the back & front.

Just to let me down I am not an expert just one who uses the stuff with about 18 months experience & gets the results (on average) that are acceptable to me. This is a confessional !

First Steve you are not giving a thorough clean. Put the nozzle in warm water as soon as you remove it. Give it a good shake (gently). Give a good riense in water. Sight thro the large end onto a well lit white surface You will see the outlet at the end which should be a nice round bright hole. If not use a reamer gently with water to clean out. Use the reamer very gently not as a battering ram. When assembled use half a cup of Vallejo A/B cleaner & spurt through.

No idea on Xtracrylx but best is Vallejo who have their own matched thinners stuff based on the constituents of their paint. Get a big bottle not the silly little ones.

Vallejo Primer is a bit thicker than the paint. I use a .4 nozzle needle now for all A/B work. I was getting a number of blocks with the .2. What size is your nozzle Steve. Whoops could have been expressed better ?

Vallejo Air is thinned but I always add about 20% Vallejo thinners. Decided it gives a better finish even if I need to give an additional coat due to the thinner paint coverage. Also thinned it dries quicker. Primer I give a bout 35% to first coat then about 20% to next coat. Should not try to cover the whole thing with the first coat,

Let us know if you need further help Steve. A thought what pressure are you using ?

Laurie

 

[tecdes]

An extra comment. Does seem as though the Xtracrylx dries quickly.

Also Model colour is really for hand brushing. If you weigh the bottle against Model Air it is as if it is a lead weight. I would say at least 50% thinners for Model Colour. The rule seems to be the consistency of milk. Whose milk I am not sure. Our Jersey Cows Milk comes un-thinned English Cows milk is getting on towards transparent. But you get the gist ?

Matter of interest what airbrush are you using Steve ?

Laurie

 

[stona]

Slightly off topic!

It is sooooo difficult to give accurate thinning ratios. I have recently thinned two different colours from the same manufacturer. I estimate that one was about 40% thinners and the other 60% to achieve a similar consistency for spraying!

Cheers

Steve

 

[Stevekir]

IanM:



Thanks. I am now clear on this.



tecdes:



Thanks for the hints on cleaning. I am learning to clean much more frequently and thoroughly.



You asked:



"Vallejo Primer is a bit thicker than the paint. I use a .4 nozzle needle now for all A/B work. I was getting a number of blocks with the .2. What size is your nozzle Steve?



Its 0.3 mm



"A thought what pressure are you using" ?



25 to 30 PSI. I tried a lower setting but didn't see much paint landing on the part, needed quite a lot of time, I thought. However, I have been using Vallejo "Acrylic Polyurethane Surface Primer 73.601" which is almost identical in colour to the gash plastic parts I am using for practice, so it is very difficult to see how much paint has gone on. I have now ordered the same make of primer but in white so that I can see more clearly what is happening. (In time, experience will tell me.)



"No idea on Xtracrylx but best is Vallejo who have their own matched thinners stuff based on the constituents of their paint."



I started on Xtracrylx (having learned how to spell it!) because they have the three colours for the early Spits (RAF Dark Earth, RAF Dark Green and RAF Sky). But perhaps I will change to Vallejo Model Air acrylics.



QUESTION: Is it safe to use a coat of Xtracrylix paint, and then a top colour coat of Vallejo Air and then another make of varnish?



"Matter of interest what airbrush are you using Steve ?"

View attachment 56413



BD 130. A very cheap one, bought in a package from airbrush-pro.co.uk. If sold separately it costs £16!!! I will buy a good one in due course, preferably with a nozzle that is just inserted rather than screwed in on a minuscule thread which is very difficult to hold and screw in. (I have a De Vilbis (I think) "Aerograph Super '63" bought in 1963 and last used 35 years ago, but it still works. However, it does not have a cup, just a slot for the paint, which can spill during use.

BTW, I am astonished at the huge amount of info (on forums and videos) on scale modelling (and everything). As my 8 year old grandson once said "Grampa. Isn't the Internet wonderful!" He's right.













View attachment 58486

 

[andygh]

Xtracrylics thinner is alcohol based, it turns vallejo paint into lumpy custard, as does Tamiya thinner

For vallejo paint you need their own thinner or some H2O

 

[tecdes]

IanM:

QUESTION: Is it safe to use a coat of Xtracrylix paint, and then a top colour coat of Vallejo Air and then another make of varnish?



"Matter of interest what airbrush are you using Steve ?"

View attachment 56413



BD 130. A very cheap one, bought in a package from airbrush-pro.co.uk. If sold separately it costs £16!!! I will buy a good one in due course, preferably with a nozzle that is just inserted rather than screwed in on a minuscule thread which is very difficult to hold and screw in. (I have a De Vilbis (I think) "Aerograph Super '63" bought in 1963 and last used 35 years ago, but it still works. However, it does not have a cup, just a slot for the paint, which can spill during use.

BTW, I am astonished at the huge amount of info (on forums and videos) on scale modelling (and everything). As my 8 year old grandson once said "Grampa. Isn't the Internet wonderful!" He's right.

Steve your concoction. Sailors have a saying "you are sailing close to the wind". Easy answer to this one experiment. If you are top coating with Vallejo why not stick to Vallejo Varnish which is very good especially with their new mixture & also they now do a polyurethene although not used that.

On the brush front not knocking what you have Steve but there has to be a great difference between a £16 & a Harder & Steinbeck or Iowata at well over £100. A replacement needle & nozzle cost in the region of £30 for each of these makes & they are probably the main key to a good air brush & the standard of finish. Although before I get re-buffed there are many who use a wide range of air brushes & find them OK.

As you must be of about the same age or near Steve we both remember before the internet. The best available was a trip to the library & Encyclopedia Brittanica or Arthur Mee's Children's Encyclopedia. Or perhaps the Eagle comic which has some info or even Cigarette Cards.



Laurie

 

[Dave W]

I use a 0.5 nozzle and spray Vallejo air without thinning.When I cant get Vallejo air I use the Vallejo model colour thinned 50/50 with Vallejo thinners.Dont use much so the 'silly little bottles' last me quite a while.Ive recently got a large bottle of Vallejo white primer and that sprays fine without any thinning.

 

[Ian M]

I have sprayed Vallejo over Xtra and also the other way around with out any issues.

I only Vallejo Varnishes, so no comment on that.

Like Laurie I use mostly Vallejo (model color). Invest in their thinners and also their Airbrush cleaner. Very good stuff. It makes short work of removing dried paint as well.

If you want to avoid screw on nozzles, Have a look at Badger. They have a couple with drop in type nozzles.

Ian M

 

[stona]

Is it safe to use a coat of Xtracrylix paint, and then a top colour coat of Vallejo Air and then another make of varnish?

Yes to the first part. A conditional yes to the second part. If you use an acrylic varnish you should be fine. A lacquer based varnish might cause problems,you'd need to do a test.

Cheers

Steve

 

[Stevekir]

My AB is still blocking up (it is the £16 job, part of a bundle, that I showed a yesterday in this thread, immediately above) and I cannot work out why. The trigger and needle seem to move correctly and there is a good flow of air and cleaner but not paint.

Sorry to bore you. Here is step by step what I have done this afternoon to demonstrate the problem which has been happening since I got the AB:

I clean it strictly in accordance with the routine in m1ks' excellent and detailed video that he referred to in an earlier post, and all the other advice on the Internet, namely:

Clean out the remaining paint in the cup;



Using a brush and Iwata/Medea airbrush cleaner clean the cup (especially the bottom near the needle) and spray through cleaner several times until it sprays clear;



Retract the needle, remove the nozzle and its two bits and soak in a pot of cleaner for 5 minutes;



Remove needle from the front and wipe thoroughly with a paper towel soaked in cleaner;



Push several times one of those special thin cylindrical brushes through the passage leading from the nozzle area to the bottom of the cup, the passage full of cleaner;



Swill with cleaner and blow through;

Using a paint brush, brush all the three nozzle bits. Blow through and, looking through a strong magnifier, confirm that the hole is clear (light shines through), especially the nozzle;

Insert needle from the front and retract away from the nozzle area;

Refit the three nozzle bits and push the needle forward until it stops, then tighten it at the back;

Spray with cleaner to confirm a good spray discharge, then spray with water.

Pour some Xtracrylix paint (RAF Dark Earth) into a small container and dilute with 10 to 15% Xtracrylix thinner as on the bottle (like milk). Add to the cup;

Start spraying at about 20 PSI (higher pressures make no difference). At first the spray is visible but immediately becomes weak. Paint builds up very slowly on the part and then stops after about 7 secs, never to reappear;

Repeat the whole rigorous cleaning as above, (adding an extra spray-through using Muc-off);

This time dilute the paint to about 40 % thinner (like runny milk);

Repeat spraying, with the same result;

Repeat the whole rigorous cleaning as above and put it away;

Having rigoroursly cleaned my (De Vilbis?) Aerograph Suoer '63 (not used since 1970), add same paint as above (10 to 15% Xtracrylix thinner added);



Result: Success!

What am I doing wrong? Is the AB faulty or damaged? Is it too cheap even to spray paint?

HELP!

Yes, I know it is very cheap. I could use my Aerograph but it has no cup and the paint spills out of the small paint slot, and it won't fit into my cleaning station/AB holder, and some air escapes from the back of the nozzle area. Or I could buy a decent AB.

Very discouraging.

 

[m1ks]

The cost of the brush shouldn't be a problem unless it's been behaving this way from the outset which might suggest a faulty manufacture or part problem.

I had a similar thing happen to me the first time I got a split nozzle, they are amazingly easy to split and very difficult to see.

Take out your nozzle and needle, using a jewellers loupe or strong magnifier insert the needle holding it with a bit of pressure into the nozzle, (don't force it as you don't want to split the nozzle if it is OK), rotate the nozzle looking carefully, if it is split, replace, (fortunately you can get a replacement needle/nozzle from ebay for about £4-5 delivered).

Another thing to check is the needle point, hold it on a sheet of glass and roll it and check it rolls true, or grip it about a centimetre from the point and rotate it checking that the point stays true to a reference, if theres the slightest hook, burr, snag or kink on the needle point this will clog faster than a fast thing.

One final possibility is an air leak at the point where the nozzle screws into the airbrush body, check the o ring if fitted, a leak here can do funny things to the paint flow.

With your other brush working on the same paint and ratios it points to one of the above.

If you do have to replace the needle/nozzle assembly, (you wouldn't be the first, I've replaced mine twice on the cheap brush in my video and once on another), do NOT buy Iwata needles or ones branded for Iwata, these are slightly thicker than the chinese copy ones use, (guess how I found out, I still have 2 0.3 (to fit) Iwata needles)

Now I run my chinese cheapie without the o ring on the nozzle which enables me to spray cellulose through it safely, however, it's a hit and miss on the nipping up part, twice i've twisted it off the threads being too heavy handed and had to replace 2 nozzles unecessarily but, (unlike the Iwata I use mainly now which seals finger tight), it has to be just right or it gets an air leak, hence the reason I always test spray some IPA through after the cleaning and before storage, it's very irritating to load the paint THEN discover you have a leak and have to re-check.

One final point, if you do , again, have to replace the needle / nozzle set, keep your old needle, (if necessary straighten it by dragging it backward through plier jaws while rotating, (hopefully you know what I mean), keep it handy in your storage box and you have a perfect nozzle reamer (used carefully of course).

Re the split nozzles, the first I caused myself through seating the needle too roughly, easily done I discovered, the second was when i dropped it off my lap, (sitting on the floor cleaning it as per the video), and it landed on the rearmost part of the needle forcing it through and splitting the nozzle) the other brush, no idea, may have been a bit iffy from new or could have been me again seating it too roughly. They are very capable but are more cheaply made than the Iwata etc. I still regularly use mine.

 

[tecdes]

Steve. After you clean the brush & connect up if you pull the trigger back (no paint) do you get a regular supply of air ?

Is the paint drying off quickly in the cup ?

Have you any other paint than Xtracrylix you could try ?

Laurie

 

[Stevekir]

m1ks: Many thanks. I will do these things tomorrow and report.

You also said: "The cost of the brush shouldn't be a problem unless it's been behaving this way from the outset which might suggest a faulty manufacture or part problem." At first it seemed OK: I was using Vallejo "Acrylic Polyurethane Surface Primer 73.601" although that airbrushing always seemed to take a rather long time to cover the part compared to videos that I have watched.

If I cannot resolve it myself (with help here) I will return it to the seller and ask for a replacement.

tecdes: Yes. Pulling back the trigger produces a strong flow of air, and also cleaner (I can see the stream). Its when the colour paint is used that it actually clogs. I'm pretty sure that the nozzle covers are not clogging, nor is the paint drying in the cup..

On trying another paint, I have one bottle of Vallejo Model Colour but as I have been told that is not ideal for airbrushing, I will get a pot of a Vallejo colour and try that. However, please note above in this message my early use of Primer.)

 

[Stevekir]

I did mk1s's tests and found no faults. I also took the opportunity to minutely examine the nozzle to check it and its surroundings and the needle to confirm that all were 100% clean and they were.

I rang the supplier, Yorkshire Clockmakers trading as airbrush-pro.co.uk offers airbrush airbrush compressor autoair paint airbrushes createx paint and they were flummoxed, especially about the way the primer did work albeit seeming to take a long time to build up coverage, and the fact that for some tests I had over-thinned the paint. He is sending me a 0.5 needle and nozzle. If it works it will probably suit me since I am not likely to be doing fine lines in the near future.

 

[tecdes]

Be interesting to know how it goes Steve.

Got to say you have patience if it had been me it would probably have been in the dustbin. Or perhaps before that I would have been banned by the Ladyship & living in the greenhouse in disgrace.

Laurie

 

[Stevekir]

Yes, the Memsahib did comment along those lines!