Alumiprep question

[Dancer]

I am just starting my RV7 and am planning to prep my parts by using Alumiprep and then Zinc Oxide-yellow-non etching rattle can.
Question: should I use a scotchbrite pad and gently rub my parts to physically etch them? The Alumiprep label doesn't say that it has a chemical etching quality and I'm not using a self etching Zinc Oxide primer.

Also, how many of you builders are choosing not to prep/primer your internal parts at all?

Lance
Tail
RV7

[plaurence]

Lance,

Alumiprep is a phosphoric acid. I would lightly scuff the part with a maroone Scotchbrite pad and laquar thinner followed by drying with a paper towel. The alumiprep will etch the metal. I would suggest to chromic convert the metal after etching (Alodine) and use a two part epoxy resin primer. If you don't take these steps, there is a greater chance of fliform corrosion.


Peter

[cytoxin]

you are kicking the hornets nest dancer but any scothcbrite pad will be fine. i however have used the grey ones (they are finer) but do you really want to sacrifice alclad for spray bomb primer. you can etch the alclad and alodine (without scotchbrite)with decent results. if you use sem etch primer (sold in many auto paint stores) i would say just hit one or two strokes with a grey pad and then wipe down with mek and hit it with the sem. if you use primer that dries slick you are good if it dries flat and rough the paint is open and no protection gained. vans tells people to do this if it gives THEM piece of mind. if you are not using a primer/sealer you are wasting time and money. ifr in doubt try this on steel and watch it rust through the primer..

for a data point i went the alumnaprep alodine and epoxy prime way. would not do it again except for non alclad parts.


ok maybe i would

[TShort]

Originally Posted by cytoxin

do you really want to sacrifice alclad for spray bomb primer

Will be interested to hear others' thoughts, but my impression was that light scuffing with scotchbrite doesn't remove the entire layer of alclad, just roughens it for better primer adhesion.

Thoughts?

FWIW, I did the etch/alodine/AKZO too.

T.

[cytoxin]

as i said before i used the grey ones mostly, and very lightly, only enough to satin the alclad.
those maroon ones are really aggressive when they are new. and the alclad is only .002 thick.
NOW, i am going hunting so while im gone try not to beat up on me too much. as i wont be here to defend myself

[vmirv8bldr]

The alumiprep label SHOULD say to follow the use of Alumiprep with an Alodine solution. If not on the label itself, read the usage guidelines that came with it. If it did not come with any, request them from the vendor.

The Alumiprep I use came with instructions saying to follow with Alodine. Likewise, the Alodine instructions say to preceed it's use with Alumiprep 33. They work as a pair.


Here's what I do:

1. Clean first with a solvent where necessary. This takes off tape residues if present, other thick oils, or sticky stuff.

2. Then scuff with a maroon pad, wipe clean with a solvent soaked shop towel. Non Al-clad stuff I scuff lightly, Al-clad stuff I scrub to a satin finish.

3. Then use alumiprep. I keep the solution in a 5-gal plastic pail. Small parts get a bath, large parts get sprayed and further scuffed with the maroon pads. Rinse clean, hang to mostly dry. (Nothing is quite as beautiful as freshly alumiprepped aluminum!)

4. Alodine. Again, small parts get a bath, large surfaces get a brush application. (Different mixing ratios) Hang to dry overnite. Dull, yellowish appearance.

5. Finally, 2-part epoxy primer.

This stuff is TOUGH!!! The SEM stuff is good, especially if you use 2-3 light coats and have roughened up the surface, but the 2-part stuff is unbelievably tough. VERY scratch resistant.

YMMV, TEHO

[AZtailwind]

I was using the maroon pads and thought they where a little heavy for the primer work, Now off to buy some gray- But I love primer debates and a true believer in sacrifice- therefore zinc chromate is my choice-
The bullets of zink on outboard motors that are continually sunk in water are the proof for me. These aluminum castings should just fall off in the water after a year or two- but the sacrificial zinc bullets keep em bolted on and alive.
Now if there is a two part epoxy (with high zinc content) for the floor boards- I am all (flame retardant) ears
Brad
RV6A
Finishing kit- panel