Insulating the Birmabrite skin from the steel door frame.

[Troll Hunter]

Further to my previous question regarding annealing of a door skin ( 29th May 2018) I now need some more advice, please.  I used the bar of soap method and all appears to be OK, and I've also finished welding (and grinding!) the door frame.  I'm now ready to recombine the two.  The original LR construction appeared to have used a glue or mastic between the steel and ali, presumably to prevent vibration and fretting, but also to prevent galvanic corrosion.  It's advice on this important stage that I am now seeking.

I'm currently thinking of using 1mm thick tar paper, as used by roofers beneath the tiles.  This I would glue to the steel frame, and wrap it around the outer edges.  I would then refit the skin with a good bead of mastic applied inside the edge before closing it onto the wrapped steel.  After the mastic has cured I propose applying a coat of autobody seam sealer around the folded edges.  But what have others done, please, since I'm sure that I'm not the first to have this challenge?

Many thanks in advance for any and all advice, recommendations and suggestions from the forum.

Mike

[ianmayco68]

I haven’t done this yet Mike , as I’m waiting on sp4x4 to get some of the bits I need back in stock before I place an order and I’m fitting new galv steel skins but I was going to use marine bond to seal the frame and skin back together.

cheers Ian 

[Scotts90]

I painted my door frames fully prior to attaching the new Ali skins, the OE has bare steel frames bonded sparingly onto the skin...just enough to trap water and start some nice reactions. Used PU body sealant to seal and bond the frames to the skin after which some silentcoat deadening was applied. 4yrs so far and no bubbles...

[Happyoldgit]

I've used plastic DPC [damp proof course] on a roll for similar jobs in the past.

[Mo Murphy]

I painted and then used sealant between the frame and aluminium skin when I reskinned my doors Mike, 8 years on and no evidence of electrolytic corrosion yet 👍

Mo

 

[Snagger]

I had my frames blasted and read oxide primed, and etched and primed the insides of the new skins.  I used a generous application of seam sealer between the two, 100% coverage for the contact areas, which was a mistake as it was too thick and make folding the lips over difficult.  It resulted in marking of the skin around the window aperture which needed filling before paint.  Next time, I'd apply the same primers, but use tape like you for a thinner, more even coverage of the entire contact face.  Even duct tape would be enough to keep the metals apart, though the cloth weave would likely absorb moisture.  A Thick plastic or rubberised tape (not foam) would be ideal.

[JohnnoK]

I have seen structures guys using buff packing tape on bits that need to be kept separated.

[Snowbird]

I use blue sheet wherever steel touches aluminium. It's a bitumen layer with a blue pvc outer skin. Used it under the bump stops, door frames, bonnet frames,works a treat.

[Paddy_SP]

I've recently done this - before I fitted the new skins though, I had the frames hot-dip galvanised. I then used PU adhesive to bond the skins in place, before applying etch-primer and then two pack Hempadur primer. I haven't got as far as applying the top coat yet though!

[Ghound]

i use this