Vallejo polyurethan varnish peeling

[SodaCitron]

Hello

 

First time using this product... I airbrush  undilluted Vallejo Polyurethan Satin varnish on top of Vallejo acrylic paint, as a protective layer. Then, after 20 hours drying time, I apply Flory wash.

 

Following this, when gently rubbing the wash with a cloth as usual, the varnish starts to peel off, like the skin after a sunburn. I was able to remove entire wing portion 😕 It seems that the water based wash has rehydrated the varnish.

 

Experimenting then with this drama, I wet the model, rub it lightly  and reproduced the same effect on unwashed section. No adhesion of the varnish whatsoever when rehydrated. Is it normal behaviour with polyurethan varnish ? I thought it was more resistant than acrylic...

 

Any similar experience on your side ?

 

[bmwh548]

To my knowledge the polyurethane stuff (primer/paint/varnish) isn't sandable cause it peels right off. 

[Matthew1974]

I've played with Vallejo's polyurethane varnish and am using it on a Zvezda Yak-3 I am finishing up now.  My first try at it was okay.  I used the gloss varnish on the completed engine, let it cure for a few days and applied an oil wash with Abteilung 502 oils and their proprietary thinner.  I let the wash dry for a few days and then went back with the Abteilung 502 thinner to clean it up some with a brush - no problems - the varnish stayed put.  Once the I finished painting the aircraft's camouflage, I applied the polyurethane varnish, this time satin, to the entire aircraft to prepare for decaling.  As I was placing the decals, I used Vallejo's Decal Softener (which has alcohol) to conform them to the aircraft.  I needed to clean a few stains from placing the decals and rubbed a bit too hard in a spot and noticed the varnish lifting a tiny bit.  I stopped rubbing and started blotting and rolling with a Q-tip - no problems the stains lifted and the varnish stayed put.  After the decals were dry, I sprayed another coat of satin polyurethane varnish to get ready for the weathering the aircraft using oil pin washes and oil dot filters (again with Abteilung 502 oils and their thinner).  This coat of polyurethane varnish has been sitting for a couple of days now.  Going to give it one more day to hopefully fully cure and then move on to the weathering.  I'll let you know how it holds up to this stage.

I thin the polyurethane varnish with Vallejo's Airbrush Thinner and add a couple of drops of Vallejo's Flow Improver.  My first try with Vallejo's primer also ended up in the primer lifting up in sheets and peeling off even after a couple of weeks of curing.  The primer is polyurethane based just like the varnish.  With regards to the primer, I found that I sprayed at way too high of pressure and way too heavy.  Following that mess, when spraying polyurethane primer I mist on coats at low pressure from about five or six inches from the model surface, allowing each misting to dry to touch before I go back over it.  After I am satisfied with the coverage and opacity, I let the primer cure for two to three days before playing with it.  I've had now problems with this.  I point this out because both Vallejo's primer and varnish are polyurethane so perhaps should act relatively similar.  

I used to use paint with enamels and lacquers exclusively until my wife really started to complain about the odor.  I switched to Vallejo this year and really had to reconsider how I finish models as they are significantly more delicate than what I was used to.  Good luck! 

[Matthew1974]

Just to follow up, I used oil dot filtering with on the aircraft today and manipulated the oil with a brush damp with Abteilung 502 thinner and I experienced no peeling of the polyurethane varnish.  Looking back, I think spraying thin coats of the varnish and giving it time to fully cure (I waited three days) really helped.

Edited December 19, 2019 by Matthew1974