Bad Reaction!

Started to paint the Rear Valance and deck lid.

The paint system I "was" using was as follows:

UPOL Acid Etch #1 - Bare metal primer

UPOL P88 High Build primer - on filler or existing paint

Cellulose Cobalt Blue - Top colour coats

So for the wings I followed the following paint system:

Paint stripped to remove all layers

Chipped out any filler

Bare Metal.

Rust converter

Sand down

Acid Etch Primer 2 Coats

Sand down

Filler work

High build primer 2 coats

Sand down

Top Coats 2 + 2 

That worked well for the wings and wanted to use cellulose paint system as its the original paint system.

Then on the Deck lid and Valance. As this was already painted and flat my plan was to sort any localized issues and paint as above just without the Acid Etch as it eats away the thin edges of paint and filler.

So Sanded down. Treated any rust. Skim filler in low spots.

So all was ready to go.

Loaded up the spray gun with Upol P88 High build primer. Mixed it to a 70:30 thinners (unlike the datasheet which says 50%!)

Spray going really well. Then moved on and turned around to see this happen!

The paint was not even holding its own weight!

It was not happening on filler but only on the old painted areas!

So after a spell of depression and despair I sanded the whole lot off and did some research.

I suspected that the previous owners had used Acrylic Paint! It's an incompatibility issue with solvents on oil based acrylic.

So I did a few test spots to confirm with different ratios of Solvent.

Sure enough same reaction! It does hold when more paint less solvent is applied but still reacts around the edges!

So I need to rethink the plan. Could use a barcoat to act as a barrier but any pinholes will cause a reaction.

So decided to try some Epoxy Primer.

So I am going to to have to cover it all with epoxy primer!

Epoxy primer is much better for rust and durability BUT it's also twice as expensive and harder to sand down flat. But needs must!

More progress to come........