Welcome to the forum, Val!  

Yes!  Definitely stay away from the typical Model Master clear coats!  I love using them but I found out the hard way on a B-36 that MM top coats do not work well over natural metal finishes.  I did, however, discover that the Model Master metalizer sealer does, in fact, work out just great and I've have very good results with it.

As a rule, Alclad paints are as hard as nails so some would say you don't even have to worry about using a sealer on it.  If you were to use it, it would just be to protect the decals.  

I hope others chime in on this topic.  I, too, would be curious to know what other types of sealers would work on Alclad.

Eric

Alclad makes their own line of clear coats. They have 1 acrylic water based gloss, and a line of enamels in gloss, semi-, and flat coat. They come pre-thinned for airbrush only. If you dont' have an airbrush I would suggest MM metalizer sealer, like Eric just said, or you can brush paint future over the model for decal work. I've found it doesn't change the metallic look much at all, and looks fine again when flat coated after the model is finished. Future brush paints pretty well, just add a drop or two of windex, and clean your paint brush with windex and water.

Welcome Val!

Yes, as Eric pointed out the MM sealer works well. Though frankly here recently I've been applying a matte coat over the decals and any gloss non-metal paint (like anti-glare panels) and just leaving the rest of the plane in the bare Alclad. It really doesn't need a protective coat at all.

Just don't apply a flat matte coat over the Alclad, it will dull it to the point it looks like cheap silver spray paint- trust me- I found out the hard way!

Welcome Val 

and like was said  MM sealer, Future or nothing for the Alcad

you can use different  Alcald types (chrome, Dull Aluminum, aircraft aluminum etc) if you want to vary the bare metal on various panels

any who,  start a work in progress post of your build so we can  look with envy at what you doin'

I have had some success with artist acrylic clear coats. As stated elsewhere here, Alclad paints are super hard. However, in my experience they do tarnish over time due to the oils in your hands when handling, and just exposure to the nasty stuff in our air. I use the acycylic artist clear coat from Hobby Lobby . No thinning and shot through a Paasche H airbrush at 25-30 psi.