Do I need to use Hammerite primer with Smothrite

[John]

I am going to be painting some steel motorbike bits with smoothrite after a good wire brushing. Is there any advantage/disadvantage using one of thier primers or should I just go onto the bare metal.

Also, is the Spray Smoothrite as good as the brush on type. Regards John

[Tim S]

I've found that Smoothrite can crack off thinner steel in flakes, if impacted (this was on a Landrover chassis, 2mm steel plate). The primer

*may* help, but I've not actually tried.

For thick metal, adhesion has always seemed fine without primer IME.

One tip I do have, if the parts are small, and SWMBO is out, is bake them in the oven at about 80-100C give or take for a couple of hours. Open all the doors and windows, it is a tad smelly - but the hammerite will finish up hard as nails.

Cheers

Tim

[Andy Dingley]

Use whatever primer you like, Smoothrite is still rubbish. Its only virtue is that it least it's not as bad as Hammerite!

They're both too hard, too stiff, too brittle and have poor adhesion. They crack off anything that sees any sort of flexing or vibration, including chassis parts.

OTOH, Finnegan's primer isn't bad.