How to polish an aluminum prop

I have an old Sensenich 74" propeller (I think from a 172) that was a
hand-me-down gift from another pilot. The prop did not pass its
inspection, and although it does not look it - the prop is no longer
airworthy.

I have had it hanging in my garage for a few years, and have decided
it would be neat to polish it.

So, what's the best technique for stripping the paint and polishing?

I spent an hour last night working on one of the blades.

I used 120 grit sandpaper to remove the paint, then progressively
sanded with finer paper (220, 320, 400, 600, 800) until reaching
2000grit. This left a smooth finish, but certainly not a mirror-like
finish.

I then used a polishing wheel on a drill with Tarnite (which is pretty
much the same as Brasso) to polish the prop.

The end result looks pretty good, and comes pretty close to a
mirror-like finish. In fact, from a distance it looks like a mirror.
However, upon closer inspection - when the light is right, I still see
horizontal streaks, presumably from the sanding process.

Will any amount of sanding or polishing remove these streaks? Is it
realistic to think more elbow grease might provide a 'perfect' finish
on the prop?

What should I do to preserve the polished finish? Wax it - car wax?
The prop will be staying indoors out of the rain/elements, so I
probably do not need to put a $100/bottle coat of NASA approved wax.

Thanks,
Nathan

Will any amount of sanding or polishing remove these streaks? Is it
realistic to think more elbow grease might provide a 'perfect' finish
on the prop?

Maybe, but you have to question its worth. We have a polished prop on
Atlas, and gave up on improving it beyone the stage you are at.

What should I do to preserve the polished finish? Wax it - car wax?
The prop will be staying indoors out of the rain/elements, so I
probably do not need to put a $100/bottle coat of NASA approved wax.

We just hit it with Mother's Aluminum polish once or twice a month.
Since yours won't be spinning on the front of an O-540, I suspect you
won't have to do it quite so often...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On May 7, 10:11 am, Nathan Young wrote:
I have an old Sensenich 74" propeller (I think from a 172) that was a
hand-me-down gift from another pilot. The prop did not pass its
inspection, and although it does not look it - the prop is no longer
airworthy.

I have had it hanging in my garage for a few years, and have decided
it would be neat to polish it.

So, what's the best technique for stripping the paint and polishing?

I spent an hour last night working on one of the blades.

I used 120 grit sandpaper to remove the paint, then progressively
sanded with finer paper (220, 320, 400, 600, 800) until reaching
2000grit. This left a smooth finish, but certainly not a mirror-like
finish.

I then used a polishing wheel on a drill with Tarnite (which is pretty
much the same as Brasso) to polish the prop.

The end result looks pretty good, and comes pretty close to a
mirror-like finish. In fact, from a distance it looks like a mirror.
However, upon closer inspection - when the light is right, I still see
horizontal streaks, presumably from the sanding process.

Will any amount of sanding or polishing remove these streaks? Is it
realistic to think more elbow grease might provide a 'perfect' finish
on the prop?

What should I do to preserve the polished finish? Wax it - car wax?
The prop will be staying indoors out of the rain/elements, so I
probably do not need to put a $100/bottle coat of NASA approved wax.

Thanks,
Nathan

As you move from one grit of paper to another you must keep sanding
until there are no marks from the previous paper discernible on the
surface you are sanding. That was the key to making plexiglass
repairs as I was taught in A&P school. The same thing would apply to
making a mirror finish in aluminum. So you choice is to go back and
resand or go with what you got.

John Dupre'

Nathan
Don't use abrasives to remove the paint - you're adding scratches that
you'll have to remove later. Try to use a good quality water based
paint remover. I just went through this discussion with my mechanic
this morning when I dropped my plane off for it's annual. He's
removing paint from an old bonanza and restoring it to it's original
polished finish. Man, that's a ton of work.

Dave
M35

Nathan Young wrote:
I have an old Sensenich 74" propeller (I think from a 172) that was a
hand-me-down gift from another pilot. The prop did not pass its
inspection, and although it does not look it - the prop is no longer
airworthy.

I have had it hanging in my garage for a few years, and have decided
it would be neat to polish it.

So, what's the best technique for stripping the paint and polishing?

I spent an hour last night working on one of the blades.

I used 120 grit sandpaper to remove the paint, then progressively
sanded with finer paper (220, 320, 400, 600, 800) until reaching
2000grit. This left a smooth finish, but certainly not a mirror-like
finish.

I then used a polishing wheel on a drill with Tarnite (which is pretty
much the same as Brasso) to polish the prop.

The end result looks pretty good, and comes pretty close to a
mirror-like finish. In fact, from a distance it looks like a mirror.
However, upon closer inspection - when the light is right, I still see
horizontal streaks, presumably from the sanding process.

Will any amount of sanding or polishing remove these streaks? Is it
realistic to think more elbow grease might provide a 'perfect' finish
on the prop?

What should I do to preserve the polished finish? Wax it - car wax?
The prop will be staying indoors out of the rain/elements, so I
probably do not need to put a $100/bottle coat of NASA approved wax.

Thanks,
Nathan

Too late to help you, but I had one blade from my Comanche which
failed inspection and being a pretty lazy guy I found a local shop
that polished it to a mirror finish for $40. Of course it is half as
long as the one you have.

Regards,
Jerry