The coat of blue on the two bottom ultramarines is just right it seems. It looks smooth and even and its not obscuring the models detail, so it seems you thinned the paint just right. As far as using that satin varnish, you should know that spray can varnish can be very temperamental depending on certain factors like room temperature, humdity or overall due point. Especially if using GW old purity seal. I'd recommend testors dullcoate since that one tends to work better despite high temp/ humidity.
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