Importance of Priming

[Adrian Harris]

There's a lot of information in the Knowledgebase regarding prepping and painting but I thought, as the Churchill contains quite a lot of mixed steel and aluminium parts, that this was worth repeating.

I'm currently stripping down and rebuilding a Comet, and this is the effect of moisture getting between un-primed steel and aluminium parts:

The rest of the bracket is fine, but the interaction between the steel and aluminium dramatically increases the corrosion to both parts.

I usually use an etch primer on aluminium parts and a zinc primer on steel parts, though you can use etch primer on both.

Adrian.

[Stephen White]

Timely Adrian. Here's the KB Topic for reference:

viewtopic.php?f=34&t=5802

[Brian Ostlind]

How old is the build!?

[Simon Peck]

Where was it stored?

[Adrian Harris]

Brian - The Comet kit came out in 2010 and I've been told this one was built fairly soon after release.

Simon - It's been dry stored for the last four years but before that I couldn't say. From the track wear I know it's been run a lot, so I would imagine it's been caught in a few rain showers in its time.

Adrian.

[Martin Usher]

Galvanic corrosion Adrian, I have had to deal with the end result of this in a few of my machine tools where the protective layer between was compromised, can be a very expensive end result if not found fast and rectified.
Martin.

[Jerry Carducci]

I agree with the others. I've had first hand experience with Galvanic corrosion. When living very close to the pacific ocean during my teen years I recall
some parts exposed to the elements; namely aluminium and steel or worse brass virtually dissolved before your eyes aided by the relative salty environment which was nearly always foggy.

Again much later when I purchased a home further away from the coast in which someone unbeknownst to me had used a steel grounding clamp on copper water pipes- very bad idea. Caused a premature pipe failure that had to be addressed.

I've not often primed or painted the interior of my smaller models, being ICE powered with the attendant oils but with these larger beasts especially where dissimilar metals are used primer is the order of the day.

Bad things can happen between certain different metals; moisture will certainly make bad things happen.

Jerry

[Gary Richardson]

Hi all

As this topic is about priming, I have a question regarding the Churchill and the primer that was used.
Am I right in thinking the early Churchills had grey primer which was later changed to red oxide primer that would have been used for the 1943/44 Mk3 AVRE tanks? The reason I ask is I am still trying to make up my mind whether to do the Mk3 AVRE with mortar, fascine rack and fascine or the desert version with auxiliary fuel tank. As I want to start priming the parts before it gets too cold to work in the garage and I really need to crack on with it over the next week or two.
I would appreciate any info from those with knowledge regarding this.

Regards
Gary