Enamel wash lifting paint

[beetcleaner]

I am building the new tool Airfix 1/48 Spitfire and am in the process of detailing the cockpit/wheel wells. All painted with Humbrol enamel and then sealed with two coats of Humbrol Clear.

Used Humbrol 78 and Humbrol Met 56 for cockpit walls and 56 for wheel wells. Made my usual wash of Windsor and Newton black and brown oil paints water down 90/10 with thinners. Did the wheel wells, let it dry for 20 mins, took a slightly damp cotton bud dipped in thinners and started to clean excess wash off.

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First go was fine but I wanted more off so did it again. Second time started to lift off the Clear and silver paint beneath it. Luckily this was in a bit that wouldnt be seen once the wings were joined. I have used this process before with no problems.

Is it the Humbrol Met 56 that is the problem? I have yet to do the cockpit/fuselage side walls and dont want to make a mess of that. They have now had three coats of Humbrol Clear.

I have some Humbrol and Tamiya black acryllic paints. Would it be better to thin those with water as this would not attack the paint and/or Clear?

Thankyou for any advice

[Greg B]

Use an acrylic varnish to seal. The thinners have done what they were supposed to do with your wash in thinning down oil based coatings.

[AngstROM]

Like the man says. The key is using 'dissimilar materials' for successive paint/varnish/wash/final clear finish. Using solvent-based thinners with an oil wash will attack paint or varnish if it has been thinned with the same stuff. Acrylics mostly use water- or alcohol-based thinners, so will resist a solvent-thinned wash. Also note that some pre-thinned task-specific washes (MIG Ammo, etc.) require solvent application for clean-up, so an acrylic varnish is a good idea.

Revell and Xtracrylic clear varnishes work really well, or a slosh of Future/Klear/Pledge or whatever it's called now will do nicely.

[beetcleaner]

Thankyou for the replies. Sorry if I'm being a bit slow but shouldn't the Humbrol Clear, which is an acryllic varnish, seal the enamel base coat and allow an oil based wash to be used?

Or does the wash eat through the Clear as well as the paint beneath. I used this method on a 1/72 Airfix Spitfire and it worked fine. If this is going to be an issue I think i'll need to move onto a water/clay based wash.

[AngstROM]

Ah, the plot sickens! Sorry, I assumed it was the Humbrol clear stuff in a jar that you thin with Humbrol enamel thinner or white spirit -my mistake.

The answer may be that the clear coat was thin enough in places to allow penetration of the wash thinner to the paint underneath -that's bitten me in the @$$ a few times, when I thought I'd put on enough clear coat to paddle in!

Another thing you can try is thinning the oil wash with lighter fluid; this evaporates so fast it may not have time to do any damage to the clear coat. Never tried it myself, but some modellers use it all the time.

[SaintsPhil]

As the others have alluded to, it'll either be the clear coat was too thin, in corners maybe, or hadn't fully cured, 24 hours is normally ok at room temperature. Equally the first application of thinners could have softened the gloss and it hadn't re-cured by the second. The other option is the thinners you use is too 'hot' I personally use low odour thinners from windsor and Newton with oils and it works ok.

[beetcleaner]

Following all the advice above I made up a wash with the Windsor and Newton mix then thinned it with white spirit and not the thinners I had been using with the enamels. It worked out fine and didn't lift any paint so I guess it must have been too "hot" after all.

I am applying every technique going on this Airfix 1/48 Spitfire Vb including washes, dry brushing, pre shading panels (never done that before) and heavy weathering as I am doing the Malta version.

Thanks very much for your help/advice