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1/72 Airfix A-4 Skyhawk; Reoccurring paint dimple finish issue.


Isamu77
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Hi All,

 

I'm very new to airbrushing, so I'm still learning the basics. A reoccurring paint issue I'm having across multiple models, paints, and airbrush equipment is when spots appear in the paint while airbrushing. Sometimes, I can apply a wet coat over these clear spots and achieve a smooth finish. Other times, these spots or dimples will remain.

I've had the same thing happen to the horizontal stabilizers on this Airfix A-4 Skyhawk. On one side, the paint went down fine but with the other, spots in the paint appeared and have not smoothed out.spacer.png

 

I'm using a H&S Evolution 0.2mm at around 1Bar, with Mr Color Gloss White, mixed with Mr Leveling thinner.

 

Other parts of the model have gone down really well but for some reason, this right stabilizer reacted this way.

 

Any suggestions why this might be happening?

 

Thanks, Michael

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Did you wash the parts before painting? 
 

Could be that the parts have some localised contamination like oil from your fingers or mould release ~ you might of tried to lay it down a bit thick in those areas as well. Some micro mesh should knock it back but I would strip and start again.

 

You should also prime with a proper primer for best effect.

80% of a good finish is based upon good prep work. 

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Well, not reading your comment I would guess, you have sprayied thick layer of very thinned water based colour onto uncleaned greasy surface. But in this case I am quite not sure about right reason. Sometimes with glossy colours there could happen "an orange"  surface, means the surface is very simmilar to orange peel surface.  But the bigger spots are not this result I think  🤨 Nevertheless I would clean the surface before airbrushing. In case it will happen again, I remember some difficulties that there is an oil in the pressured air from compresor which can degrade colour quality. But it is really mere speculation...

Edited by David Koktavý
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There are few things that might be happening here. Here are few suggestions:

1) What paint/thinner proportions did you use? For that nozzle and pressure I would expect something around 60/40 to 80/20 but exact proportions everyone figures out on their own by more practice. It is very possible you thinned it too much and it simply was flowing on the surface after landing on it.

2) Did you try to lay the paint in one go? This is another common mistake that I did when started with A/B. You should not try to paint it in one layer. It is better to do in a few thin coats instead of one thick layer. With one thick layer there is a huge chance of flooding some area (which is actually looks like what happened there). 

Additional things:

3) Did you prime the model before laying paint? Some paints might not adhere very well to the plastic (usually water based acrylics like Vallejo, Model Master). Tamiya & Mr. Color seems to be better, however I would still suggest laying a layer of Mr Surface Finisher 1200 or 1500 before applying paint: it makes paint to adhere better and it also allows not to worry about washing the model before painting if there are no visible contamination by release agents (I usually wash only resin parts). It also unifies the color so if let's say you used green putty to patch up some seam lines and other imperfections that green color would not be visible through the paint layer (especially would be visible on gray/white airplanes)

4) What distance were you spraying from? Standard mistake (I know I did it when got my 1st A/B) is to try to use it as spraygun and spraying model like from 30-40 cm... This is not the right way to do it: 10-15 cm is usually max distance. In reality is even less.

5) Nozzle size of 0.2 is really good for some delicate work (maybe things like preshading, marbling, some sort of freehand camo, etc) or trying to paint small areas. However when you learn basics I would probably advise getting 0.4-0.5 nozzle (you are going to need it in the future anyway to paint bigger areas -- cannot imagine painting 777 using 0.2 nozzle).

 

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1 hour ago, Dads203 said:

Did you wash the parts before painting? 
 

Could be that the parts have some localised contamination like oil from your fingers or mould release ~ you might of tried to lay it down a bit thick in those areas as well. Some micro mesh should knock it back but I would strip and start again.

 

You should also prime with a proper primer for best effect.

80% of a good finish is based upon good prep work. 

Thanks for the response.

 

I usually wipe the parts down with 91% alcohol but I can't remember for sure if I did it this time.

 

I did use Mr Surfacer 1500 though. Should I be washing/cleaning parts after priming, if handling the model afterwards?

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54 minutes ago, Doom3r said:

There are few things that might be happening here. Here are few suggestions:

1) What paint/thinner proportions did you use? For that nozzle and pressure I would expect something around 60/40 to 80/20 but exact proportions everyone figures out on their own by more practice. It is very possible you thinned it too much and it simply was flowing on the surface after landing on it.

2) Did you try to lay the paint in one go? This is another common mistake that I did when started with A/B. You should not try to paint it in one layer. It is better to do in a few thin coats instead of one thick layer. With one thick layer there is a huge chance of flooding some area (which is actually looks like what happened there). 

Additional things:

3) Did you prime the model before laying paint? Some paints might not adhere very well to the plastic (usually water based acrylics like Vallejo, Model Master). Tamiya & Mr. Color seems to be better, however I would still suggest laying a layer of Mr Surface Finisher 1200 or 1500 before applying paint: it makes paint to adhere better and it also allows not to worry about washing the model before painting if there are no visible contamination by release agents (I usually wash only resin parts). It also unifies the color so if let's say you used green putty to patch up some seam lines and other imperfections that green color would not be visible through the paint layer (especially would be visible on gray/white airplanes)

4) What distance were you spraying from? Standard mistake (I know I did it when got my 1st A/B) is to try to use it as spraygun and spraying model like from 30-40 cm... This is not the right way to do it: 10-15 cm is usually max distance. In reality is even less.

5) Nozzle size of 0.2 is really good for some delicate work (maybe things like preshading, marbling, some sort of freehand camo, etc) or trying to paint small areas. However when you learn basics I would probably advise getting 0.4-0.5 nozzle (you are going to need it in the future anyway to paint bigger areas -- cannot imagine painting 777 using 0.2 nozzle).

 

Thanks for the suggestions. Here's my responses:

 

1. I was using 1:2 paint/thinner, so around a 70/30 mix.

2. I had this happen before with the same parts, so I sanded them down with Tamiya sanding sponge 3000 before trying again. I did try and build some layers but was probably too impatient when reapplying additional coats.

3. I did use Mr Surfacer 1500.

4. Since upgrading to the H&S Evolution, I am spraying much closer, maybe 3-5cm away for those parts.

5. The H&S did come packed with the 0.4mm nozzle, which I was just using for priming. So I'll try using that more then.

 

Thanks for the advice, much appreciated.

 

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22 minutes ago, Isamu77 said:

Thanks for the response.

 

I usually wipe the parts down with 91% alcohol but I can't remember for sure if I did it this time.

 

I did use Mr Surfacer 1500 though. Should I be washing/cleaning parts after priming, if handling the model afterwards?


I don’t normally wipe down again after priming as it’s normally one of the last things that’s done before the top coat goes on. At this point handling is kept to a minimum and the parts have a suitable handle on as to avoid it. 
 

I can only think that something has gotten on to the primed area on your wing for it to fisheye like that fella or the primer might not have cured properly? If the primer has gone on without any issues then you shouldn’t have any issue with the topcoat. 

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