Pre- Cleaning parts

I would suggest a coat of good primer after washing and drying the parts, such as Tamiya Fine Surface primer or Model Master primer.  That should take care of the adhesion problem.

Not to be insulting or impolite but are you using a dish washing soap (designed to cut grease better than hand soaps) and then gently scrubbing the parts, on all surfaces with a small brush (old tooth brush or

a new one from the 99 cent store?

If you were to miss a side or end of a part, that, could be the root of some of your adhesion problems.

Then as Cadet Chuck  stated a good primer coat and you should be golden -or DUNKELGRÜN-or Dark Earth -or... oops got carried away again

I pre wash my models with warm water and DISH soap like lemon joy. I let it soak for about 15-30 minutes and rinse with the sprayer from the sink with warmer water and set to dry for the rest of the day. I then use Model Master Enamel grey as a primer through an airbrush for the base and Valejo Model Air Acrylic thinned down with a little windex. Comes out PERFECT for me.

I've been using grease cutting dish soap (as DUSTER suggested) and an old toothbrush to scrub the parts, I soak for about five minutes overall, then rinse well and dry with a cloth.  PollyS also makes a plastic prep liquid which seems to be mostly alcohol.

Tamiya recommends to gently sand all parts with 1000 grit or finer sand paper, but I never do.

I know its not good practice but I dont think I have ever washed one sprue from a kit, ever. I did however pick up a Zvezda Mig the other day that had so much release agent on the parts that the plastic bags were literally stuck to pools of it on the wings. I've had a lot of luck with Tamiya tape and the blue low tac masking tape. Also, I prime with an enamel primer and also finish with acrylics exclusively.

It's pretty rare for me to wash a kit, too. I'll do it on resin or short run, little known kits. Most of the time I'll just hit the sprues with a coat of Model Master gray or white primer. I've only encountered one kit that I ever had problems on. That was the old AMT 1/650 (or so) TOS Enterprise.

Steve,

yes dish soap, but not soaking, just brushing; the water is pretty hard; I do brush pretty carefully though. Thanks for your help, I am using primer now, with better results.

Thanks, I am using primer more, and I think results are improving.