Glass Bead Media Testing on 5906 Frame

The final recommendation for those that do not want to read the entire post and accompanying responses.

Media:
McMaster-Carr 3398K41, Glass/Aluminum Oxide, 120-170 particle mesh size, 120 grit

Pressure:
60-70psi

Nozzle Distance:
4-6 inches

The recommendation above is taken from BMCM's post #18. My manually blended media would probably be closer to McMaster-Carr 3398K41 (Glass/Aluminum Oxide, 170-230 particle mesh size, 180 grit). This media would be fine for removing light scratches and shiny areas, but may not have enough tooth to retexture a repair or an area that has been sanded smooth.

--- Back to the original post ---

Here are the results of some media testing I did on a junk 5906 frame (5906 Abuse (Cracked Frame)).

Media Tested:
Ballotini: 170-325 grit, #13 glass beads (GB) purchased from Grainger
Pro-Blast: 80-120 grit, #9 glass beads (GB) purchased from ebay (seller: tacomacompany)
Baking Soda: Arm & Hammer
Central Pneumatic: White Aluminum Oxide (WAO) 220 grit purchased from Harbor Freight (It looks like Harbor Freight has discontinued the 220 grit WAO; this outfit seems to have small quantities at reasonable prices: Panadyne Abrasives)

Note: Media blends are by volume not weight.

Equipment: Speed Blaster gravity fed blaster running at 70psi (except as noted)

PPE: Goggles, respirator, 7mil nitrile gloves, bandana to cover head, ear muffs to cover ears, mechanics one piece suit – I’m blasting outside, not in a booth.


Testing Round One (R1):

Picture #1: in the middle of the trigger guard you can see four finishes coming together. The top left is #9GB only, the bottom left is #9GB + soda, the top right is #13GB only, and the bottom left is #13GB + soda.




Picture #2: left is #9GB, middle is original, right is #13GB




Picture #3: left is #13GB + soda, middle is original + soda, right is #9GB + soda




Picture #4: inside the trigger guard there is a faint line in the middle, the original finish is on top and the original finish + soda is on the bottom.




My impressions on the first round of testing – the #13GB cleaned up the frame much fastener than the #9GB, but the #13GB media left a slightly brighter finish. The soda did a good job at cleaning, but did not remove any of the scratches. When I was blasting with the soda it looked like it was darkening the frame, but after I cleaned it off, the finish in the soda blasted areas was a little lighter.


Testing Round Two:

Picture #5: left is R1 #13GB, upper side of dust cover is a 1:1 WAO/#13GB blend, lower side of dust cover is #13GB at 100psi.




Picture #6: left is R1 #9GB, middle left is 1:4 WAO/#13GB blend, middle is original, middle right is R1 #13GB, right is 1:1 WAO/#13GB blend.




Picture #7: left is #13GB at 100psi, middle left is R1 #13GB + soda, middle is original + soda, middle right is #13GB at 110psi, right is R1 #9GB + soda.




Picture #8: left is R1 #9GB, right is 1:/9 WAO/#13GB blend at 60psi.




Picture #9: 1006 blasted with 1:10 WAO/#13GB blend at 60psi. The sight recess was masked and retains the original finish, the surrounding areas were blasted.






Picture #10: 1006 blasted with 1:10 WAO/#13GB blend at 60psi. The middle recess of the back strap was masked and retains the original finish, the surrounding areas were blasted.




My impressions on the second round of testing – glass beads at higher pressure do provide a flatter finish than lower pressure settings, but the finish is still lighter than the original. Adding aluminum oxide does dramatically change the finish color/brightness. The first blend of 1:1 was surprisingly dark, even the second blend at 1:4 was very dark, but the third blend at 1:9 with lower pressure was very close. It was a little darker when compared to the original finish on the 5906, but when I compared it to the original finish under the grip of a 1006 it was near perfect. I altered the ratio one more time and blasted the 1006 with a 1:10 ratio (5 tsp of WAO per 1 cup of #13GB @60psi); it turned out excellent.


Final Comparison Photos:

The following pictures show the blasted 1006 with some of its brethren that still wear their original finish. I took the photos with and without flash to show the finish in different lighting. The top pistol is a 4506-1, the middle is the blasted 1006, and the bottom is an original 1006.














The only difference I can find is that the blasted 1006 does not feel as smooth as the other two, but this could be because the finish is brand new and the other two have smoothed out over 20+ years.



Here is an bonus picture showing a comparison of WAO grit I used on a project 645 awhile back (645 before and after)

Media Tested:
Abrasive Armory: White Aluminum Oxide 120 grit purchased from ebay (seller: theabrasivearmory)
Central Pneumatic: White Aluminum Oxide 220 grit purchased from Harbor Freight

Picture #11: the knife is 120 grit, the saw blade is 220 grit



I also picked up another 645 recently and had a little refinishing fun (645 Refinishing Fun).

skjos - Great info and pictures - Thank-you! I had heard about baking soda being used but had never seen the results. These post is a keeper for me ...

Edited to ad: have you had any problems with the trigger play spring or it's rivet during/after re-finishing 3rd Gen's? Understand this was a junk frame so you may not have messed with it.

I'm gonna ask the really stupid question here.

The baking soda: are you saying that you mix the baking soda with the beads, and then apply that combination using the blaster, or are you saying you blast with the beads and then follow up by cleaning with the soda by itself by hand?

I've never bead blasted anything, so I don't know anything about the soda component. Guess I'm wondering if the soda by itself on a rag, for instance, is a cleaning agent in its own right.

I blasted with the glass beads first, then with the soda. The soda was applied with the blaster at the same 70psi setting.

I understand the factory used a blend, aluminum oxide & glass beads. No idea of the mesh size or mix ratios though.

Cheers
Bill

What media best replicates the factory finish? I have a project that will need a bead blast when done. Thanks

03Fatboy said:

What media best replicates the factory finish? I have a project that will need a bead blast when done. Thanks

Click to expand...

Both the #9 and #13 are brighter/shiner than the factory finish. If I can find the time in the next few weeks, I'll try blending #13 and 220 grit aluminum oxide and see what happens.

The secret sauce has been found. I'll elaborate more when I can get some pictures up.

skjos said:

The secret sauce has been found. I'll elaborate more when I can get some pictures up.

Click to expand...

Just in time, looking forward to your report. Thanks for the effort!

Whatever you use (abrasive paper of media blasting), it will be a good idea to dip everything into a citric acid solution as a final step to passivate the SS surface. The citric acid removes any free iron on the surface and makes it more corrosion-resistant. Many super markets sell a product called "Lemi-Shine" which is a powder used in kitchen dish washers to remove streaks on glassware. It is nearly pure citric acid. Citric acid solution is also good for cleaning brass cartridge cases. And it's not hazardous like nitric acid would be.

Baking soda (sodium bicarbonate) blasting is most often used for removing softer materials from metal, such as paint. I am surprised it would be abrasive enough to have much effect on SS.

I've updated the original post with my second round of testing. BMCM was correct in that the finish is best replicated with a WAO/GB blend. More specifically, 1 part White Aluminum Oxide 220grit mixed with 10 parts #13 glass beads (5tsp of WAO to 1cup #13GB) run at a lower pressure 60psi.

I may test passivating the 5906 frame with citric acid, but I'll need to do a little more research into temperatures, time, solution ratios, etc.

Thank you for the doing all this testing. The information you've compiled is quite valuable. My current blasting setup is loaded with 270+ beads. I do need something with more tooth to replicate the factory finish after I've done a bunch of metal work. I've been meaning to set up another small cabinet with a blended abrasive media and what you've done here will certainly guide my choice of media.

By the way, not sure if you are aware, but stainless steel once cleaned will passivate by itself merely through exposure over time to atmospheric oxygen. In a week or two the protective layer of chromium oxides will form and the steel will be every bit as passive had it gone through a brief nitric acid bath.

Cheers
Bill

I've been using crushed walnut shell 25# packs from Harbor Frieght...
but the GB looks more like what I want...

Although, from the pics, could barely tell any diff from #9 to #13...

There is not much of a difference between #9 and #13, both are brighter than the factory finish, but #13 is a skosh lighter than #9. Also #13 removes surface scratches faster than #9 due to more media striking the part.

Added some comparison photos of the blasted 1006 with its siblings that wear their original finish.

skjos: You undertook a tremendous amount of work (hassle) which has now provided this forum with valuable information. It deserves every one of the stars now appended to your post.

It'll benefit a lot of folks - me being among them as I've wondered time and again, "What kind of media?"

And who would've imagined the aluminium oxide having such a pronounced contrast range?

You've spared me a huge amount of work and, more importantly, a screw-up, followed by another, and another, and . . .

Thank you, Sir!

DC

I'm glad to help out; I hope members will post their results to this thread when they give the 1:10 220WAO/#13GB formulation a go.

I finally got around to cleaning out my cabinet and changing the blast media to something with more "tooth" and Skjos's thread here seemed the obvious place to share my results.

I had been using some 270+ straight glass beads from Brownells. While that stuff was adequate for cleaning and some removal of light tool marks it would not replicate the original blast profile that S&W did.

Today I loaded my cabinet with the #4 Econo blend from Mcmaster-Carr
McMaster-Carr
This media is a blend of aluminum oxide & glass beads of 120-170 mesh size.

Today I ran some parts through using that media at around 80psi and keeping the nozzle 4-6 inches from the workpiece.

I'm very pleased with the results....

Here on the left is a 4513 just blasted next to a unmolested 4516-2 slide. Near as I can tell the surface profile is identical between the two, just a little brighter on the 4513.


Here is a 1066 slide that had a horrid dremel hack job done to it. It's been welded, ground, milled, filed & sanded. There's no evidence that anything was ever done and the finish is blended perfectly.


If anything I may back off on the air pressure a bit for the next run. In any event, I can't complain a bit with these results.

Cheers
Bill

Thanks for all your hard work and for giving us all the secrets.[emoji106]

Insofar as my eye is concerned respecting the two side-by-side slides, the "lighter" difference could be fully attributable to lighting - as in that light which existed when the image exposure was undertaken.

Absent of my ability to get really, really close to each of the two slides, the grain of each mimics the other in the supplied images.

Furthermore, it's reassuring to see what a, um, "revised" slide reveals after getting beaded: nothing but a nice-looking finish.

Thank you for posting your results.

Later.