What is the best abrasive for aluminum

[nickao]

Okay what is simply the best abrasive paper for my Festool RO 150/3 to sand raw plate aluminum after a fine drum sanding? It is cast aluminum so it is soft and easily sandable..

There are so many Mirka products for sanding  aluminum my head is spinning. I could easily spend 500.00 to find out. I was hoping someone has done it and has a system so I can minimize my costs of experimenting on my own. I could easily get a uniformed very light even textured finish using the Festool papers, I want to get a high shine so its a lot tougher. I tried a few Festool papers, some even  made for polishing, but they are simply not good enough. The metal needs a lot more prep.  The festool vlies is not suitable at all, it falls apart long before I get the desired results. I am thinking of the Platin, but Mirka seems to offer a lot more selection and grits for metal than does Festool.

I have been looking at Mirka Abralon(would this work), but it is expensive as heck, anything cheaper that could be recommended?

I know the regular Mirka Gold works pretty well with aluminum(at least for the lower grits before high polish), what would be the equivalent paper in Festool?

The metal is getting prepped for paint so no polishes that leave any type of interfering residue can be used. I am not looking to buff out the aluminum, but to prep it to use a nice high gloss paint.

Thanks for any input you can give.

 

[billg71]

If you're painting why worry about a polished finish? I have friends in the auto paint business and they usually go 80-120 grit on bare metal, apply a couple coats of high-build primer and from there out they're finishing the finish.

Aluminum's a little more complicated to prep but once it's primed it's no different from any other painting schedule.

And the Abralon works great, it's a lot cheaper cheaper to buy in quantity than the two-packs from Woodcraft or Amazon. Check these guys out. Or a local auto-body supplier.

Best of luck,
Bill

 

[nickao]

For whatever reason even 220 grit is leaving a very textured finish on this cast aluminum, not what I would call smooth, not even close. Most autos now are not aluminum like I am using so I am not sure comparing current auto body  work to "cast" aluminum works.

I should clarify. I am using a special anodized look paint. A solid primer can not be used underneath, there can be no building up of primer. The special primer for this product is clear and will show every imperfection underneath.. The metal must be smooth and shiny  to get the anodized look to work. Actually a finished Chrome would be perfect for this product. This anodized look spray needs the underneath metal to show through. This stuff sticks to shiny metal becasue a clear adhesive is used right after the primer so the final anodized look paint sticks.

I have tested this paint factory fresh aluminum and it is fantastic, but the parts I  am using were cast by a friend using scrap auto parts and getting them to look like factory fresh aluminum is turning out to be a bit problematic. I have the clean up and the shine, its just the little, itty, bitty scratches that are the issue.

Thanks for the link.

http://www.duplicolor.com/products/metalCast/

Using the "ground coat" you can use this on wood and other non metal too for some awesome results:

http://www.duplicolor.com/success/stories/tqlLKyVfiw

Here is a similar product like I am going to use:

Metal Cast:





This red color is close to what I am going to use:

http://www.duplicolor.com/products/metalCast/

 

[Qwas]

Metal needs to get sanded much farther than 220 for a smooth finish. 400 and even 600 grit will leave a rough finish.  I recommend going to at least 1000 grit and perhaps 1500 grit. No need to get anything fancy, normal aluminum oxide sandpaper works fine but silicon oxide will last longer.  I use the wet/dry type and use water as my lubricant. Be sure to clean and wet the sandpaper regularly.

Here is an eBay supplier I use regularly: http://www.ebay.com/itm/380375375017?ssPageName=STRK:MEWAX:IT#ht_918wt_907

 

[nickao]

Metal needs to get sanded much farther than 220 for a smooth finish. 400 and even 600 grit will leave a rough finish.  I recommend going to at least 1000 grit and perhaps 1500 grit. No need to get anything fancy, normal aluminum oxide sandpaper works fine but silicon oxide will last longer.  I use the wet/dry type and use water as my lubricant. Be sure to clean and wet the sandpaper regularly.

Here is an eBay supplier I use regularly: http://www.ebay.com/itm/380375375017?ssPageName=STRK:MEWAX:IT#ht_918wt_907
[/quote

Well that's exactly what I thought until a person said their friend only sanded to 180 on autos. I think that is more for initial repair and filler work.

 

[AlexThePalex]

I would start with Titan, go from 400 to 800 to 1200. Perhaps even higher. From there on, you'll need to polish with compounds to get a shiny result.

Well that's exactly what I thought until a person said their friend only sanded to 180 on autos. I think that is more for initial repair and filler work.

That's only the first prep work on bare metal. The bare metal gets sprayed with fillers and primer, and that gets finished by wet sanding up to 1200 before the final layer is sprayed on. 

 

[nickao]

I'll give the Titan a shot.  

I am a wood guy, for finish and painting metal I am a Newb.

Here are pics of Metal Cast spray being used on wood(the top looks like mdf), with curly woods it sure looks nice:

 

[billg71]

Oh, I see... That ain't paint, it's more like a tinted clear coat. If I remember from the detailing days, you probably want to wet-sand up to 1500-2500 grit with a silicon-carbide paper or pad and then shoot a test piece. Depending on the result you might need to polish it off with a buffer and an auto polishing compound. I wouldn't worry too much about residuals from polishing, just wipe the piece down with denatured alcohol before you spray on the adhesion coat.

Looks interesting, please post some pix of the final product.

Best,
Bill

P.S. Here's a link to the Mirka website page on solid-surface finishing and their recommendations.

 

[greg mann]

You can get a mirror finish with various grades of steel wool, and it's cheap. One of the problems you are probably up against is that CAST aluminum is often very porous, and I would especially think so if it were done in a home brew foundry. Not trying to cast aspersions on your friend's capabilities but modern aluminum foundries use polished steel molds and 'pressure cast' methods that mitigate porosity (air bubbles) by forcing them out of the molten metal. Porosity can't really be polished out as it appears as small specks on the surface. That said, I wish you success and would be very interested in a few shots of the finished product

 

[ach_78]

Hi,

I have a different application for sanding aluminium, I have an aluminium PC case made of 2or 3 mm thick aluminium that I'd like to refinish.

It is now a brushed finish, I wonder if I could get a fine random "tumbled" finish using my orbital sander. The surface really isn't large at all, could Granat sand paper do for a such a small job ?

thanks for any feedback

 

[waho6o9]

https://www.lumberjocks.com/topics/273377

Post #13 by John Smith may help you out.

Best of Luck. 

 

[Michael Kellough]

Hi,

I have a different application for sanding aluminium, I have an aluminium PC case made of 2or 3 mm thick aluminium that I'd like to refinish.

It is now a brushed finish, I wonder if I could get a fine random "tumbled" finish using my orbital sander. The surface really isn't large at all, could Granat sand paper do for a such a small job ?

thanks for any feedback

Yes you can, using any abrasive. Use very light pressure and test/practice to get the pattern you want. But start with the finer range like 400 grit. Unwanted heavy scratches will be a pain to remove.

 

[ach_78]

Thanks