I'm working on Revell's 1/72 scale U-Boat and have hit a snag. About 10-14 days ago I applied a wash of black oil paint (W&N) thinned with mineral spirits (before applying the wash I sprayed with Model Master clear acrylic gloss and allowed it plenty of time ot dry). As of today, I'm still able to wipe away most of the wash with my finger or a cloth. It doesn't seem to be drying and adhering to the surface.

Have I done something wrong? I want to apply additional washes in the form of filters but am afraid that it will just wash away what's there now.

Any suggestions will be greatly appreciated.

Thanks.

Brian

Hi Brian,

I could be mistaken but I think the gloss coat airbrushed prior to the oil wash is acting like a barrier. I encounter the same 'problem' with airbrushing Future prior to oil washes.

You could airbrush another coat of gloss to seal in the initial wash and then add additional wash layers.

Frank

If the oil paint is thick enough it will take a very long time to dry by our normal modelling paint standards. I remember the first time I tried it and was still able to move paint around weeks later...

You might try a test with some paint drier... I forget the exact term; but there is an accelerator for oil paints. I'm not sure how well one could apply it AFTER the paint without affecting the appearance though, which is why I suggested a test. Also, you might talk to some figure painters who use oils to see what they say.

Gloss varnish and oil washes is a NO-NO combination for weathering large surface areas unless you want to enhance panel lines and therefore ''channel'' the oil washes to certain places which makes it a bit easier as the oil slides on the panels till it reaches the edges and then gathers and resides within the panel lines (aircraft mostly) .If you can replace the gloss with a semi gloss even better.As its been said above gloss doesn't allow a) for the oil to penetrate or been absorbed by the the color underneath it and give it that difference in tone you looking for and b) as you said it doesn't provide any surface with grip for the oil to hang on.Besides, gloss surfaces in real life very rarely appear to have the same aging effects as mat or semi-gloss colors do, with variations in hue, saturation etc.Most likely in most cases they would be chipped/cracked as the gloss paint is build up as a thin but hard layer .And definitely you would not have any glossiness left in any color even if it was initially gloss ,being under water for that long as in a submarine.

Here are my two cents ...

From all I know acrylic paints as well as laquor dry through vaporescence of the thinner.

Oil paints work quiet different since they dry through oxydation.
The binder within the oil paint reacts with oxygen hence the paint will gain weight when dry.
There is no true way to accelerate the oxygen process.

Knowing this tells us that the thicker the oil paint was applied the longer it will need to dry.
A comon problem and benefit of oil paints at the same time.
The slow drying time ensures most likely a crack free and lasting result.

This is the reason painting in oil takes such a long time.
One has to apply very thin coats of paint and wait at least 2-5 days before you can even think about moving on. The thicker the layer the longer the forced break.

To accelerate the drying process of oil paints one can buy desiccative products. Be aware that as much they accellerate the drying process (it is not so very much as one would wish for in scale model building) they at the same time harm the binder.
Again, the oxydation process is not accelerated.

Usually someone doing oil paintings aplies the oil paints (=medium) "fat over lean" since the fat medium transferes some of the oil into the lean medium underneath it.

For a quick lookup on what to be aware of, I found you this list:
Click: 10 Oil Painting Tips

As for your model I can see no way to help since whatever technique available requieres to be done before you apply the oil paints.

Just to round up my input let me tell you

1. that it will help to apply the medium on rough cardboard and pick it from there before applying it to the object. The cardboard will soak some of the binder (the oil within the paint in this case) so less oil will be included and results in a faster drying time.
   
2. You can use some amount of turpentine as diluter with oil paints before you apply the paint to the object.
   

Both methods will help to make the oil paint dry faster since they thin out the binder within.

For this and in answering your question you may have to wait (up to one year depending on the thickness of the oil paint layer) because the gloss acrylic layer beneath the oil paints applied will not soak any of the binder.

Hope this helps some

mmmm....

first question to you is what the purpose of your wash was...was it to accent panel lines or change the tone of the base paint? For panel lines, you did the right thing...Gloss cote (I use future), then apply wash. Im VERY currious why its taking so long to dry...it shouldnt. The amount of oil paint actully in the wash is so small it should be dry within a day or so (not a year later!)

I wonder if it is your choice of thinning agent. I have never tried mineral spirits with oils, and always used Turpinoid (in the BLUE-WHITE can, NOT the green can!). I wonder if the mineral spirits is retarding the drying, or there is some reaction with the acrylic coat you used.
have you used these same items before with no problems, or is this the first time trying this combination?
Andy

Thanks Andy. You're correct in assuming that I was trying to accentuate the U-Boat's panels, crevices, etc. This is nothing different from what I've always read and seen done. Two of my sources were DVDs. The first was "Realistic Armor Finishing Techniques" by Compendium Films featuring Marus Nicholls. The other was "F.A.Q." by Night Vision/MIG Productions. Both of these are excellent DVDs.

I actually used two different thinners in two different locations on the U-Boat. On the deck I used Turpenoid (blue can not the green) and on the hull sides I used mineral spirits (recommended in the MIG Productions video). I got basically the same result with both thinners, though the Turpenoid seemed to produce a more "gunky", sludgy feel. There was no overlap of areas.

I intentionally used the acrylic gloss coat because I was told if I used a lacquer-based gloss coat the thinners I used with the oils (mineral spirits, Turpenoid, etc) would attack the gloss coat and then get at the paint.

I'm really at my wits end. I'm afraid my only alternative may be to give it another clear coat before applying the filters and then give it a final dull coat when it's all dry. Whenever that may be.

Brian

wow...you got me stumped. Sounds like you did all the right things...however your discription of the resulting wash from turpioid disturbs me. I have used the stuff for years and never had a "gunky, sludgy" feel. I wonder if you have a bad tube of oil paint? (hard to beleive if its Windsor Newt brand).

interesting...

you know, you could clean off the wash with some turpinoid and a toothbrush/ rag...or even just a damp paper towel woudl do the trick and try again with a different tube of paint. Just do a small area...it shoudl dry in less than 24 hours.

Andy...I had wondered about the possibility of a bad tube of paint. In fact, because of that I changed tubes between the two washes (i.e., the one of the deck and the one on the hull sides).