Applying and repairing Alclad

[Hobbes]

I've been using Humbrol Metalcote for natural metal finishes. Now I've found that you've got very little time to polish the Metalcote out before it's completely dry, so this limits the area you can cover in one go. I'm working on a Tupolev-114 that needs to be mostly in NMF, which is way too much to do in one go. So it's either multiple spray-dry-polish-seal-mask cycles, or use another product, which leaves me with Alclad.

Problem is I've never worked with Alclad.

- the Tupolev is now covered in Humbrol 1 primer. Alclad being lacquer-based,  I suspect I need another base coat?  
- the cabin roof of the aircraft needs to be white, the rest will be aluminium. Should I do the white part first, or the alu? (again, to avoid reactions between the Alclad and Humbrol enamel white)

[bodgybuilder]

Hi
Alclad needs a gloss black as the undercoat.
Matthew

[Ian the Kiwi Herder]

Alclad needs a gloss black as the undercoat.

Only if you are polishing it !! - If you plan on doing a 'weathered' NMF, then any tone of undercoat/primer is OK.... this is currently on my bench http://www.swannysmodels.com/yabb2/YaBB.pl?num=1256574387, as you can see a reasonable NMF without glossy black undercoat.

Good afternoon, Harro 
I understand you're dilemma and here's my thoughts. You could spray an overall coat of (any) Alclad straight onto the Humbrol primer and in theory it should be OK, however..... and I appreciate that this is going to cause some extra work, I would strip off the Humbrol primer and re-spray with Halfords - or any equivalent - car primer straight from the rattle-can. The only alternative to this if you are going down the Alclad route, would be to seal-in the Humbrol primer with a good coat or two of Johnsons Kleer/Future wax.

With you're primer applied, you can airbrush any Alclad tone(s) you want, but there are a few 'ground rules' (and I make no apology for repeating them once again):

1 Coats & Pressure
Two or three thin coats at low pressure - no more than 15psi. The first coat, if sprayed thin enough wont look like you have applied any paint/lacquer at all, the second coat, and it should all look right, the third coat an it will be right. You will have a superb, bulletproof and consistent metal finish as a base.

Allow a good hour or two between coats depending upon the 'atmosphere' in you're spraying area, which brings me to:

2 Atmospherics
Alclad hates cold/damp spray areas ! - If you have either, or worse, both then the lacquer will dry looking opaque, matt white and have the consistency of fine orange peel..... and is the world's worst job to remove. I have personal experience of this.... trust me.

You need a constant mild temperature with as little humidity as possible.

3 Masking
No problem. If everything goes to plan and you have the aforementioned consistent bulletproof base you can mask it that evening and spray more coats of NMF to get the multi-toned effect, or any acryllic or enamel paint. It's cellulose lacquer, once dry - as I say in optimum conditions, an hour will be fine – it is impervious to any masking you can name.

Harro, If you have any more questions or concerns, drop me a PM, or even have a word with Andy (General Melchett), he uses Alclad even more than I do, I'm pretty certain he'll back-up what I've said here.

Best of luck.

Ian
(Gatherer of Hunters and frequent user of Alcald !!)

[Hobbes]

I finally applied some Alclad to my Tupolev. Overall, I'm pretty pleased with the results; it went on easily. It does show up flaws, though. The model looked perfect in primer, but with the Alclad on, small defects have become visible. I don't see how I can repair these without rebuilding the entire wing, though, so I think I'll declare victory and move on.




Oh, the glare!

[Ian the Kiwi Herder]

B E A U T I F U L   

Was I reight, or was I right 

Ian

[Hobbes]

Ian, thanks for your advice. Feel free to add an 'I told you so' now, cause I didn't follow all of it and things have gone rather wrong. I've been masking off the Alclad to paint various smaller areas, and today when peeling off the masking tape, some of the Alclad went with it.

I left the Humbrol base coat as it was, and sprayed the Alclad straight over it. A test showed that this should be ok, but apparently the test wasn't representative of the base coat on the Tupolev. Some of the areas that are now damaged, have a coat of Mr. Surfacer underneath the Humbrol primer. Don't know for certain if that's the culprit, though.

For now the plan is to finish painting the smaller areas, then mask all of those and redo the Alclad.

[Hobbes]

I'm getting ready to have another go at the Tu-114. As said, some of the Alclad came off when I removed masking tape. I could just put another few coats of Alclad on the offending areas, but I suspect that would leave me with a weak paint layer.

I've sanded down the problem areas, to make sure there are no loose bits of Alclad waiting to fall off. I was thinking of masking the panels that need to be resprayed (so any border around the new paint would coincide with a panel line), putting a new layer of primer on, then spraying Alclad over that.
I'm planning to prime with Mr. Surfacer. Being lacquer-based, it would adhere well to whatever's underneath, and I've read elsewhere that it's usable as a base coat for Alclad.

Is this feasible? Or will I introduce more problems by applying mr. Surfacer over Alclad?

[Ian the Kiwi Herder]

I honestly don't know the answer to that, Harro, 'never used Mr Surfacer.

Ian