Paint help, please...

I'm working on a model, and I got a really nice matt grey base down with the airbrush. Then went for the 'dirt' coat, as I call it, which is a black wash which gets wiped off again, leaving the 'dirt' in the cracks and crevices. I used enamel for the base coat, and to prevent the black wash from taking up the base coat, I used a water-based thin black for the dirt coat. I had to thin it with detergent, otherwise it would bead on the surface of the enamel base.


Problem was that it dried very rapidly on the surface, so now I have dirt over everything, and my nice light grey matt coat is now a dark dirty grey all over. The detail looks really good, but the dirt goes too far, and it's really horrible and smudgy all over. In a couple of places, I did get a good result. Some areas got the best result by wiping the undiluted paint on with my finger, and then wiping it off with my finger. Other places I got good results by painting on the detergent diluted paint, and then spraying with water to clear the flat areas - and then carefully mopping up drips as they formed, until it dried.


I tried a few things to rub the dirt-coat back again, to get back to the base coat, but the only thing that moved the dirt coat was turps, and this also removed the base coat, so now I am getting back to an unpainted model, and I figured it was time to leave it alone and ask for some advice.


I'm wondering what's the best procedure for a dirt coat, should I go for a water-based base colour, and an enamel dirt coat? Would this work better? Or do I have to clear-coat the enamel, and then use an enamel? Problem is I really liked the flat grey of the enamel base coat, so I don't want to gloss clear it. Then if I use a water-based clear, it will probably not stick well to the enamel base, and if I use an enamel clear, then it will dissolve with the dirt-coat too, so again I will have trouble wiping the dirt coat.


How can I achieve this dirt-wash over my enamel base?

Best way to use a wash is with a brush I use oil based paint and use a darker shade of the original base coat


If your using a tan or a brown then a dark brown at the wash , I only use black on a dark colour and highlight raised detail with a lighter colour to get the contrast right

The way that I did my "dirt coat" was to dilute acrylic with the correct thinner for the paint approximately one part paint to two parts thinner then apply this using a washing up sponge. This just seem to add a dirty appearance to the paint work. Then I gloss coat before weathering. O ce completed the I matt coat.


Hope this helps.

Thanks Alan. I'll try this on a spare piece, but doesn't the enamel wash take off the base coat? Even just brushing on thinner takes the base coat back off. (I've let the base coat dry for several days first, so it should be pretty dry.) My base coat is a matt light grey, so it really shows up if there is any of the wash over the main surface.

\ said:

The way that I did my "dirt coat" was to dilute acrylic with the correct thinner for the paint approximately one part paint to two parts thinner then apply this using a washing up sponge. This just seem to add a dirty appearance to the paint work. Then I gloss coat before weathering. O ce completed the I matt coat.
Hope this helps.

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Do you use an acrylic base coat, or do you do this over enamel?

\ said:

Thanks Alan. I'll try this on a spare piece, but doesn't the enamel wash take off the base coat? Even just brushing on thinner takes the base coat back off. (I've let the base coat dry for several days first, so it should be pretty dry.) My base coat is a matt light grey, so it really shows up if there is any of the wash over the main surface.

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As long as the base coat is completely dry you can use oil washes with no effect to the base coat


Here's an example View attachment 110951

View attachment 110952

The best way to apply a wash to add depth & highlight detail is to apply a gloss coat over the basecoat.


Not only will this put a barrier between the the 2 applications, it will also help the wash flow by capillary action into panel lines, around bolt heads etc.


I use enamels as my base, then a few coats of Humbrol Clear & then a wash of oil paint.


However, you really should leave each coat to cure (not just dry) for at least 24 hours - most paint ' disasters ' are caused by rushing things.

Hmm, I left my base coat to 'cure' for about four days, and a quick wipe with a paper towel wet with thinner will take the base coat right back off. I'm also finding the dirt wash doesn't flow into the details - I need to brush it on and give it a quick wipe down to get it back off the accessible areas - but as I described, any wiping takes the base coat off, with either the Tamiya thinner, or turps. I tested on a patch that was last coated more than a week ago! I'm using Tamiya enamel paint for the base coat. I also tried some Revell black that I sprayed more than a month ago, and Tamiya thinner didn't touch that, but turps took that off quite easily. What am I doing wrong?


For those using enamel wash, are you able to wipe down the wash without it wicking out of the details, and lifting the base coat? Perhaps I need several coats of clear to try to really protect the base coat, to give me a small time-window to work it before I get down to the base coat?


Alan, you have got a nice looking result there. Did you clear between the base coat and the wash?

Maybe some paint techno speak here!


1. Applying any thinned paint, like a wash, to matt paint is actually a ' filter '. Matt paint at a microscopic level is very rough & the thinned paint gets trapped in the tiny pits & hollows.


By it's nature, the areas most susceptible to this are larger flat sections.


Notice how on Alan's Crusader there's very little wash around the rivet heads.


2. Most gloss clear coats used by model makers are acrylic based. This vastly decreases the possibility of a reaction between oil-based paint (oils & enamels) .


Any properly cured clear coat will not be attacked by an oil-based wash, so there isn't a short ' window '. I let the wash dry & use tissue & cotton buds to wipe it off. With the gloss coat (s) down it comes off very easily.


There is another option which is the range of Flory washes. Many people swear by them, although I've not used them myself.

\ said:

Hmm, I left my base coat to 'cure' for about four days, and a quick wipe with a paper towel wet with thinner will take the base coat right back off. I'm also finding the dirt wash doesn't flow into the details - I need to brush it on and give it a quick wipe down to get it back off the accessible areas - but as I described, any wiping takes the base coat off, with either the Tamiya thinner, or turps. I tested on a patch that was last coated more than a week ago! I'm using Tamiya enamel paint for the base coat. I also tried some Revell black that I sprayed more than a month ago, and Tamiya thinner didn't touch that, but turps took that off quite easily. What am I doing wrong?
For those using enamel wash, are you able to wipe down the wash without it wicking out of the details, and lifting the base coat? Perhaps I need several coats of clear to try to really protect the base coat, to give me a small time-window to work it before I get down to the base coat?


Alan, you have got a nice looking result there. Did you clear between the base coat and the wash?

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Cheers , Yes I did but I used a matt coat as it's easier to keep the wash where you want it and being oil paint you can mess with it , if you use a thicker wash you can get a nice water mark , good thing with oil paints is if you get it wrong you can just remove it with thinners and start again

Hi Dubster. Hmm, yes I had wondered about the matt base. Perhaps that is the root of my troubles. It makes sense that the wash would stick to the flat areas, and that's exactly what I don't want - and the main problem I had with my original method of the acrylic wash. It just wouldn't wipe back off nicely. I had put it down to drying too quickly, but perhaps it wouldn't have been an issue on a gloss base. A gloss finish is not what I want, but perhaps I need to work with gloss (or anything but matt) and then do a final matt clear coat over the top of everything to get rid of the shiny.


With the acrylic clear, will this go on OK over an enamel base colour?


Thanks to all for your help. I'm off to bed for the night, but I will experiment further and hopefully find a good result before I make a complete mess of it all.

\ said:

Cheers , Yes I did but I used a matt coat as it's easier to keep the wash where you want it and being oil paint you can mess with it , if you use a thicker wash you can get a nice water mark , good thing with oil paints is if you get it wrong you can just remove it with thinners and start again

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Your matt clear, was it enamel or acrylic?

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Hi Dubster. Hmm, yes I had wondered about the matt base. Perhaps that is the root of my troubles. It makes sense that the wash would stick to the flat areas, and that's exactly what I don't want - and the main problem I had with my original method of the acrylic wash. It just wouldn't wipe back off nicely. I had put it down to drying too quickly, but perhaps it wouldn't have been an issue on a gloss base. A gloss finish is not what I want, but perhaps I need to work with gloss (or anything but matt) and then do a final matt clear coat over the top of everything to get rid of the shiny.
With the acrylic clear, will this go on OK over an enamel base colour?


Thanks to all for your help. I'm off to bed for the night, but I will experiment further and hopefully find a good result before I make a complete mess of it all.

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I don't want a gloss finish either as all of my builds are military, so I always apply a matt coat at the end.


There's absolutely no problem with using acrylic over enamel - as you've already discovered it's the meeting of 2 oil-based substances that causes the problem!


This is the sequence I follow :


Basecoat of enamel paint


Gloss coat of acrylic gloss


Application of decals


Wash of oil paint & weathering.


Matt coat & final finishing


Obviously very simplified, but you get the idea!

\ said:

Your matt clear, was it enamel or acrylic?

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It's acrylic but you don't really need to as long as the pain is completely dry you get the same result

Just as an example of the ease of applying a wash over a gloss coat, this is my SU 152


View attachment 110959



View attachment 110960



As you can see, I wasn't too fussy about where the wash went.


Left it to dry & then wiped it off, et voila!


View attachment 110961



View attachment 110962

I've done more experimenting, and found the root of my problem - not using the right thinner. I had been thinning my acrylic with water first (very bad - because it beads on an enamel base) and then windex, which stopped the beading, but I think was drying way too fast, and not wiping off the flat areas as well. I tried a whole lot of different methods on test pieces, and as soon as I used the right thinner for the acrylic wash, it went on much better, and wiped off much better too, even with the matt base coat and no gloss coat between. The acrylic gloss with an enamel wash is something that I am keen to try in the future, when I get some acrylic gloss, but I'm getting good results for what I need in my current project. I also noticed that while my turps was just stripping the enamel base coat right off again, the enamel thinner is much milder. It will still strip an enamel gloss coat, but much more slowly, and requires a bit of rubbing.


Anyway, time to strip back some major parts of my model and give it another go. I could maybe get away with painting on top of what's there, but that's going to give me a lot of layers of paint, and maybe not so good a result.


Thanks for your help - I've certainly learned a lot!

Thanks again for all your help. I've completed the model, and posted some photos here...


http://www.scale-models.co.uk/threads/star-destroyer.31543/


In the end, I acrylic gloss coated under the wash coat, and then spent a lot of time cleaning the wash coat off as best I could. The base coat did still come off in a few places, so I did have to touch-up the base coat again, but not too much. It is such a detailed model, that what I wanted in the end was just a tiny amount of wash coat left to pop the details without making it look too dirty. The final result is combination of all the different methods on top of each other.


The matt clear was nowhere near as matt as the matt paint - more like a satin clear really, almost gloss in places, and very variable, but I've accepted it and moved on. It's time to forget the details, sit back, and enjoy the finished model.