Painting Problems

[Neil10]

Assembling the hull on my first boat kit went quite well although I had to use a moderate amount of filler to address some planking challenges. The filler came from a reputable model boat supplier and was nicely soft enough to easily sand into shape when dry. Time to paint….and that’s when the problems started.

 

Minimal adhesion of paint over any filled areas. Removing masking tape pulled off acres of paint and I’m left with a mess. Suspect that I may have to sand it all off and start again. For paint I was using brushed acrylic and a rattle can of touch up paint. No undercoat. For tape I was using Frog plus a commercial pinstripe for the water-line. 

 

Where did I go wrong? Suggested solutions please!

[Jörgen]

I think you need to have a primer before the acrylic paint. Something I have used on wood with filler with good result is tamiya primer on rattle can. I also only use tamiya tape for masking. Here is a trick to put the glued part of the tape on the top of your hand to take away little of the glue before you use it. This is quite common in plastic aircraft modeling.

 

Jörgen

Edited July 14, 2021 by Jörgen

[Jaager]

Sand off the paint that is not right.  Buy a can of shellac (clear or garnet) and one of shellac thinner (likely ethanol).  Make a mixture of thinner and shellac 1:1.  Use a piece of an old T-shirt  to pad it on - just wet no build up.  When dry, dress it with a Scotch Brite pad and tack rag it.  Give a thought to doing another coat of full strength shellac.  A better base for follow-on paint would be difficult to find.  It dries fairly quickly and is not messy.

[James H]

Seal the filler using a varnish or primer before painting. Painting on top of filler will generally mean a bad finish.

[vaddoc]

I very much like the Humbrol spray primer. Goes on thin, sandable, dries quickly, does not smell.  Comes in white, red and grey (most versatile). It will cover everything and solves adhesion issues.

[Neil10]

Thanks for suggestions. Decided to sand everything down, spray a primer coat and start again. However will use low tack painters tape for general masking this time and try to detack pinstripe tape before applying. 

[Thukydides]

On 7/14/2021 at 5:33 PM, James H said:

Seal the filler using a varnish or primer before painting. Painting on top of filler will generally mean a bad finish.

 

I. Very familiar with the processes for getting a good finish on plastic, but what to do on wood at this scale is a bit new to me.

 

Do I need to use a wood specific primer or can I use a plastic model primer I have on hand such as vallejo or badger stynalrez?

 

For vanish again do I need to use wood specific ones or can I use hobby plastic model varnishes such as vallejo?

 

[kurtvd19]

I have used Stynylrez for many wood models and it has filling properties.  I would use wood varnish myself.  Have no idea if plastic varnish would work - actually I don't even know what you mean by plastic varnish other than the Tamiya name denotes plastic.

Reverse the question - would you use wood varnish on plastic?  Not trying to be a smart*** but I find it a logical question that can guide many decisions with unknown materials.

[Thukydides]

2 hours ago, kurtvd19 said:

I have used Stynylrez for many wood models and it has filling properties.  I would use wood varnish myself.  Have no idea if plastic varnish would work - actually I don't even know what you mean by plastic varnish other than the Tamiya name denotes plastic.

Reverse the question - would you use wood varnish on plastic?  Not trying to be a smart*** but I find it a logical question that can guide many decisions with unknown materials.

 

By plastic varnish I just meant the primary audience is for plastic models (see the picture below). I wouldn't use "wood varnish" on plastic models because the only ones I am familiar with are designed for use on say furniture. In a pinch I could use a spray can of clear varnish from the hardware store but where it is not specifically designed for small models the results might not be as good or I might get a bit of a tint etc... I guess my question relates more to if I can use many of my acrylic based products that I already own on wood such as the below Vallejo product.

Edited July 31, 2021 by Thukydides
Added more detail for clarity

[Roger Pellett]

My cynical response to this is “chemistry is chemistry, the rest is marketing.”  The label on your bottle describes it as a polyurethane varnish.  That might mean that it’s no different chemically from the polyurethane varnishes sold for woodworking applications.   Try it on a piece of scrap and see what happens.

 

I also like the Tamiya primers.  

 

If you bought the filler from a hobby shop, it might actually be some kind of plastic material, so your sealer is actually sealing the plastic.

[kurtvd19]

I agree totally with Roger.  I believe what you show is compatible with wood - but try it to see.

 

[Seems ok to me]

I have had terrible experience with both wood and plastic for Vallejo primer (falls off if you look at it funny) and Badger was mediocre at best. My black Vallejo primer has been relegated to making washes or just filling in unseen areas. So far, tamiya rattle can or just plain old primer/filler or enamel primer have worked the best. Both tamiya and primer/filler sand wonderfully.  Seems like the more odorous the primer, the better the adhesion so I have pretty much given up on acrylics for priming except for miniatures.