Shroud painting

[OZ_BN1]

From the archives I have seen that the painting of the aluminium shroud is quite tricky. While I am not planning on doing the painting, I have removed all the old paint and filler and sanded by hand back to bare metal. I plan to do this to all the panels.

My question is, as the painting is some time away, should I be coating the shroud with something for short term protection?

Cheers

 

[Cottontop]

I wouldn't bother with prepping for paint now.

Most of the reason for prepping STEEL now would be to minimize rust at paint time. The shroud won't rust.

IF you prep for paint now, when your paint time comes, no matter how you prep it now, you'll have to re-prep it anyway,

Besides, bare aluminum looks way more kewel than primer.

Tim

 

[zblu]

there is a specific etch primer for ali, i would prime and store, stops the ali forming an oxide again

 

[Keoke]

there is a specific etch primer for ali, i would prime and store, stops the ali forming an oxide again. Similarly, treating the bare steel panels will prevent surface rust----Keoke

 

[HealeyRick]

Easiest thing would be to treat with Alodine until you're ready to paint: https://www.aircraftspruce.com/catalog/cspages/alodine1201.php

 

[dancrim]

I use a product called Ospho. It's a rust converter for steel
but it works great on aluminum. Aluminum oxidizes fast so
you should prep or etch it prior to painting or the paint could flake.

 

[Cottontop]

As I was rebuilding my Healey, except for Alodine, ALL of the aluminum pre-paint preparations that I looked into (nearly all contain some formulation of phosphoric acid), state that if the final paint coat is not applied within a short period (48 hours for some, 2 weeks for others) of application the aluminum must be re-prepped before the final paint coat is applied.

Do the preparations that you all are suggesting have a similar clause ?

I didn't pre-prep mine 'cause I didn't want to do it twice.

Tim

 

[Cottontop]

I use a product called Ospho.

Ospho is one of the metal preps that I looked into when I restored my Healey in the mid-90s. Ospho is not a paint, but a watery thin phosphoric acid solution.

I called Ospho and talked to an applications engineer. I asked the question. "If I use your product now and don't paint for 6 months, what will I need to do before I do the final prep for paint"

He replied that I should lightly sand the surface (probably removing the Ospho?) then reapply Ospho and let dry before priming.

I left my F/R shrouds bare metal for nearly 3 years, much of that time on the patio, then block sanded, epoxy primered, and Deltron base/clear painted. It has held up well for 15 years.

My point to the original poster was that if you are going to have to sand and prep the shrouds then, why sand and prep the shrouds now ?

Tim

 

[mjobrien]

Agree you should coat it to stop the oxidation, I had everything put in a primer as a preventative step and allowed me to not worry about it for a few years (yes took a few years to revisit the body).

One observation is have a really good inspection done. These old Alum shrouds get very fine hairline cracks that show up in paint later :wink:.....

Whoever paints it needs to understand they might have to fix one or two.

 

[Cottontop]

should I be coating the shroud with something for short term protection?

OZ,

I have given my opinion and seem to stand alone. That's OK... Like noses, we all have an opinion.

Whatever you choose to coat your aluminum shrouds, remember, paint primers are a VERY porous coatings and really don't provide much protection to the underlaying material. Aluminum can oxidize and steel can rust right through them. If that happens and you paint without removing the primer coat down to bare metal, the paint will just seal any problems under it.

Remember also that if you coat the topside, you should coat the bottom side. If one side needs protection, they both need protection.

I'm with HealeyRick, if you must coat your shrouds, use Alodine. It is by far the easiest thing to do, now and to deal with when you are ready to paint.

Again, just MY opinion, but I, personally, have successfully prepped and painted 5 cars.

Tim