Grit for prepping an aluminum hull?

[Siwash]

Hi folks

I have decided to paint my old aluminum Starcraft. I understand that it should sanded down prior to painting. What grit should i use? 180? 220? And, should it be aluminum oxide?

Should I wash and dry the boat down prior to sanding it then wash it again afterward?

It's an old boat and the paint is worn and scratched but not peeling.

Thanks in advance!

Siwash

 

[djpeters]

Re: Grit for prepping an aluminum hull?

I'll help keep this at the top as I would like to know this exact thing as well.

Thanks.

 

[Siwash]

Re: Grit for prepping an aluminum hull?

I do remember someone stating that 220 was the proper grit . . nit sure and I don't want to go ahead without confirmation!


Hopefully, someone knows on this forum!

 

[RicMic]

Re: Grit for prepping an aluminum hull?

Its not all that critical, you just want to remove the oxide and any loose material and etch the surface so that the paint has some bite. If you are doing it by hand I would use a sanding sponge or scotchbrite pad, which you can wash out and reuse. I wouldn't go any finer than 220 or medium. I use Tide laundry detergent to clean and etch the surface of aluminum, one aluminum boat manufacturer recommended it to me and I haven't found anything better for prepping aluminum.

 

[Siwash]

Re: Grit for prepping an aluminum hull?

Aluminum oxide paper?

Thanks

 

[Woodonglass]

Re: Grit for prepping an aluminum hull?

Welcome to iBoats! Scotch Brite pads work great for scuffing the already painted portions and the Not painted portions. No Primer needed on Painted portions BUT any unpainted aluminum MUST have a self Etching primer applied if you want proper adhesion of your paint. Final sanding after applying the self etching primer would be 180 wet sanding and then I always do a final wipe down with acetone and a tack cloth prior to shooting or rolling the paint.

I'm just sayin...

 

[ezmobee]

Re: Grit for prepping an aluminum hull?

Correct info above from Woodonglass. I was able to find Duplicolor's etching primer at Pep-Boys for a reasonable price in rattle cans. You only need a light dusting of the stuff.

While the advice that you don't need to prime the existing paint job is technically correct (and I've repeated it to numerous others) I am currently experiencing MAJOR failure on my own paint job. I used Petit Easypoxy and applied it directly over a prior paint job that was in good structural shape and was thoroughly scuffed. Something is causing a massive adhesion issue. Not sure what, but I gotta wonder if I'd primed maybe all my paint wouldn't be falling off

 

[Woodonglass]

Re: Grit for prepping an aluminum hull?

Having spoken with EZ' about his painting issues in the past, I Too wonder the same. It might be prudent to go ahead and prime the whole thing just to make sure the paint has a proper bonding agent.

I'm just sayin...

 

[Siwash]

Re: Grit for prepping an aluminum hull?

thanks! will let you know how i make out . .

 

[djpeters]

Re: Grit for prepping an aluminum hull?

Correct info above from Woodonglass. I was able to find Duplicolor's etching primer at Pep-Boys for a reasonable price in rattle cans. You only need a light dusting of the stuff.

While the advice that you don't need to prime the existing paint job is technically correct (and I've repeated it to numerous others) I am currently experiencing MAJOR failure on my own paint job. I used Petit Easypoxy and applied it directly over a prior paint job that was in good structural shape and was thoroughly scuffed. Something is causing a massive adhesion issue. Not sure what, but I gotta wonder if I'd primed maybe all my paint wouldn't be falling off

EZ.....did the Easypoxy stick to the areas that were primered over the bare aluminum?

 

[ezmobee]

Re: Grit for prepping an aluminum hull?

EZ.....did the Easypoxy stick to the areas that were primered over the bare aluminum?

So far yes. None of the blue seems to be falling off either. Just the white below the water line.

 

[sschefer]

Re: Grit for prepping an aluminum hull?

I used Interlux on the bottom of my Tinny. I sanded with 80g and any bare spots got taken to a bright white metal look. I used their 2 part etch/primer then 5 coats of their barrier coating and finally 5 coats of VC performance epoxy.

It's been two years and not a problem anywhere. On the above water line areas I prepped the same way and used the 2part etch/primer then their two part primer and finally the Perfection top coat. No problems there either.

I have a sand blaster now and would use that on the bottom if I did it again.