Halfords Primer

Andy T

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I agree with Mike. In my day job we call them mechanical or chemical Adhesion.

Mechanical adhesion, where the coating just "sticks", can be helped immensely by sanding or otherwise roughening up the substrate, often referred to as "giving it a key".

Imagine looking very close up, the peaks & troughs caused by the sanding scratches increases the surface area many fold, giving more area for the coating to "stick" to.
 

andy55

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I use some IPA (IsoPropylAlchohol) to take off the acrylic, just put some on some kitchen towel and rub off. Then wash your hands after.
Got some coming this afternoon. Just done a shed load of priming so having a break.
Slightly off topic but many years ago someone on the old MM forum had a theory about primers. He said that acrylic primers relied on a glue like adhesion to stick to the plastic etc whereas lacquer primers actually ate into the plastic surface and bonded that way. I don't know how true that is but it sort of makes sense.
Anyone shed light on the veracity of the theory?
Jim, very true, lacquer (cellulose) is designed to eat into the surface. And Acrylic is designed to attache to the surface.
After using the Halfords, there's certainly something 'extra' in there.
 
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