View Full Version : Al Oxide blasting substitute?
June 24, 2005, 05:13 PM
OK - the only thing Gun Kote will recommend for prepping a gun for the coating is Al Oxide. This is almost impossible to find at 120 grit unless you want a 50 LB bag - $50. Can you substitute fine sand? Anyone have experience?
June 24, 2005, 05:45 PM
Harbor Freight has AlOx on sale right now for $20/50lbs
June 24, 2005, 10:30 PM
Most of what HF sells is 70 grit al oxide. I would give the folks at TP tools a look. They sell several different choices that are the equivalent to 120 grit. The thing you can do is use the 70 grit and back off the pressure too. I blast a good bit using the 70 grit and control the surface this way. I normally blast at 140-150 psi and blast up close for the parkerizing I do. I use a good bit of the Lauer's coating and when I use it I back off to about 2" to keep from roughing the surface to much. If I need to I also back the pressure down as well. I generally don't like my surface very rough when I use the paint, but rough enough to accept the parkerizing. I have bought the 70 grit from HF when it is on sale, but I normally buy either from Eastwoods or TP tools. Good luck.
June 25, 2005, 02:02 PM
Eastwoods has some small bags for touch up, but I have to wait until Monday to see what MESH it is - I want to lean towards 120, to get it smooth. A local guy has black beauty coal slag 30-60 - what is this?
June 25, 2005, 05:34 PM
Never heard of it. I would definitely check out TP tools. Here's a link for something I think would be very effecient and cost effective for what you want to do.
It will leave the exact finish you need to paint the metal like you want. I like to blast the finish to parkerize it first and then paint over the park. It leaves a good hard as nails finish that if scratched, the park will show and not bare metal. Good luck making your decision. It is hard to find a supplier for the small bags of al oxide unless you get the heavier grit.
June 26, 2005, 06:28 AM
According to a buddy of mine who works for a company that does nothing but blasting, black beauty is just what you said it is - coal slag. The waste product of very efficently burning coal. He doesn't know the exact composition of the stuff but it is used quite frequently as a blasting media. It's not as hard as aluminum oxide so it won't bore a hole through the piece as fast as other medias. On the down side... it won't be as agressive if you need to remove some heavy scale or want a rough finish.The 30-60 is probably the grit size range in the bag
June 26, 2005, 10:24 AM
If you are looking for a small quantity of 120 grit for a airbrush-size Badger blaster or the like, Brownells sells it. Aluminum oxide blasting media are available there in either 6 lb. or 15 lb. quantities. They used to be graded FINE, EXTRA-FINE, and ULTRA-FINE. Currently they are graded EX-COARSE, COARSE, and FINE. I don't know what that change means? The old version FINE was 120 grit, I believe, so call their tech support to find out what the current grading system translates into? 800-741-0015.
Also, take a look at www.tenring.com for other blasting abrasive recommendations.
June 26, 2005, 01:40 PM
All here - THANKS much! I appreciate all the returns on this post - I'll do some more investigation.
BTW: Bownell's does list for Coarse Al Oxide (which the product number leaves me believing it is 120) for $20 for 6 LBS. Hopefully my friends gun would work fine with it. Will this be OK in a regular blast gun/cabinet?
June 26, 2005, 01:54 PM
Would this Badger "hobby" blaster do guns with the Al Oxide included? I cannot tell, but can it run on canned air. I may have to call.
(I want to do my CZ 75 AND Mak).
June 26, 2005, 02:06 PM
I use two types of media in two bead blasters. I got tired of changing media and so I just go to the other blaster now. I have some copper mine by-product that I call the Black S**T from Ajo. I use this after we use the glass/alox blast on the rest of the parts. It is mainly for the top and rear of the slides. I have no idea of what the grit is on either one. I just "Get R Done".
June 26, 2005, 04:23 PM
double printed again
June 26, 2005, 04:24 PM
I wouldn't think you would want to try to blast using that particular blaster. It is mainly used for precision etching of glass. I would suggest having a local auto shop or machine shop or gunsmith if you can find one blast it for you if you don't have access to a larger balst cabinet. You can build a small cabinet or buy one from harbor Freight for close to $100. Check out the folks at TP tools like I mentioned earlier, they have plans or you can join the homegunsmithg forum and they have plans in a pdf file that you can download. Email me and I might be bale to find a set of plans I had at one time. I built my cabinet myself from a set of plans I bought at TP, it is a 48x24x 24 cabinet and I used their glove and window kit as well as a few other Parts for around $300. The thing is, you can always find something else to blast so the outlay isn't really that bad in the long run. I saved myself a lot of money in the long run since I built myself a $900 cabinet for a little over $500 if you figure in the labor and materials. Almost forgot to mention that I looked up the directions for the Norrels and they suggest using grit in the 70-90 grit range, where did you read they suggested 120 grit? Good luck,
June 26, 2005, 08:03 PM
I have a buddy with a blast cabinet. I may punt and do a matte finish blue this week - unless I can get the elusive 120 MESH Al Oxide. How much will I need? I know I do NOT need 50 LB, and don't want to spend the money and have it laying around. Brownell's is steep. (My buddy doesn't have it). KG Gunkote recommends only Al Oxide 120 MESH. If I go that route, I will go with this recommendation.
June 26, 2005, 09:23 PM
What does the buddy use to blast with. You can achieve the finish like you need by adjusting the proximity to the work with the nozzle. I have a buddy who uses the KG gun kote and he blasts using the 70 grit like I do and his guns turn out very nice.
June 28, 2005, 05:36 AM
I have found a guy who will do it (local blaster). He has 120 MESH Al Oxide, and will do my CZ 75 and Mak for $25.
1) I have friends on another forum who say I shouldn't /can't leave the guns overnight there.
2) What do I tape up and avoid blasting? I have good masking tape (3M painters tape).
3) I figure i would be better off with a professional blaster at the "right" grit, than with 70 (I can buy it at Harbor freight for $30), doing it for the first time myself. My friend uses only glass beads. I want to follow directions from the Gun Kote people, and get a smooth finish. I think the 70 would turn out coarser no matte what I did... What say you?
BTW: Is playground sand more or less course than 120 grit???? 70 Grit???
June 28, 2005, 10:42 AM
Masking tape is paper and will be eaten through by blasting media. You need to use rubber tape so the abrasive bounces off. I have used rubberized electrical tape with some success, but you have to stop and check its condition from time to time. You can get it at Lowe's. Better is a thin neoprene tape with a PSA (pressure sensitive adhesive). I've bought this surplus before and it can be had in large quantities from Anchor Rubber or other outfits that apply PSA to the raw material. This material is also sometimes available as small round spots to serve as electronic project box feet. These are perfect for masking holes. Try Radio Shack.
Putting FFL considerations aside, you want to be there and watch the process anyway. You want to mask parts that don't receive the new finish, and because the blast stream tends to lift the edges of any masking material you stick down, you want the fellow operating the cabinet informed to avoid blasting straight at those places anyway. In particular, worry about pin holes or any other tight tolerance points. Check with the finish manufacturer for more specific information and ask whether he has any information specific to your gun?
I had mentioned the Badger air brush earlier because I assumed you having such a device explained the small quantity of abrasive you wanted? Using it with canned air would not make it. That stuff gets cold an loses pressure fast, after which you have to wait for it to warm up before the next short blast. You'd need a small compressor and a lot of patience. I've used one with the fine grade aluminum oxide to prep sight blades for a really matte black oxide finish, since my cabinets have only beads or coarse oxide. You could do a whole handgun, but it would take an hour or two and some skill to get it even. You'll make an abrasive mess in the process. The one advantage would be the small blast stream lets you more easily avoid places you don't want blasted.
June 28, 2005, 11:28 AM
done it again
June 28, 2005, 11:30 AM
Brian, I usually use oak dowel rods and then chuck them up in my drill press and turn them down tho a taper using a rasp. I drive them in with a rubber mallet to make sure they are tight. They make plugs out of silicone and the blasting man should have a set of these. Make sure to plug both ends of the barrel. I use sandblasting tape which is close to 1/8" thick to cover anyplaces that I don't want blasted, then man should have this as well. On most guns, I simply remove anything that I don't want blasted such as sights. If I cannot remove them, I apply the spray designed to hold the tape down, let it dry, and then apply the tape. This keeps the tape down where I want it to stay. Plug any holes with a toothpick or dowel rod of the appropiate size and then start to blast. I always like to spot check a place that will not be seen like the grip section of a frame first to make sure I am getting the finish I want. If all is good, then I blast the whole part. When I remove the parts, I wear rubber gloves and then use a high-pressure air hose to blow the parts off first, then I usually go straight to my parking tank. For you, I would suggest blowing off the parts and then using some kind of rust preventative to spray all over the parts and make sure to leave the plugs in place and slide the parts into a plastic bag and tie the bag up removing as much air as you can before tying the bag closed. When you get them home, I would use the rubber gloves to remove them from the bag, and then apply MEK or laquer thinner or Prep to remove the oil you sprayed on them. Do this several times and then rinse off in hot water and watch and see how the parts dry. If the water looks like it just vanishes off, then you're ready, if it hangs on the part for a while, I would do another treatment of the degreaser and then wash it off and blow it off using high pressure air again. The reason I use the oak dowels is so I can use them to suspend the barrels by wire when I paint them. I use stainless wire to hang the other parts. You should be ready to apply the paint now. I didn't ask, but how will you be apply the Gunkote? Make sure you shake the can for the appropriate time the can says to, don't shake it for a minute and say you're ready because the paint has particulate matter that has to be shaken pretty well to mix it into the paint. If you are using an airbrush, I would set the psi to 30 and check on some scrap how the pattern looks. For an air gun, I like to start at around 40psi and work up or down from there. Make sure to keep the right distance from the parts and make smooth even passes. Good luck with the project. Show us some pics when you get it done.
June 28, 2005, 04:20 PM
All: Good tips.
I have a CZ 75 PreB. It is TOTALLY detail stripped. I would only tape up the underside of the slide, and maybe some of the inside of the mag well, and/or the frame, which is already blued black. I suppose I can use a tough tape. It doesn't need plugs. (I don't think)
I have a dilemma with my Makarov. It is a Russian, and I have a replacement sight for the rear. HOWEVER, I cannot get the rear sight off because of the confoundedly small retaining pin. It needs a 1/32 punch and NO ONE make one. I have destroyed a micro screwdriver trying to get it out. I am considering drilling with a 1/16th drill bit, but I don't want to screw up the whole gun. I have a Mak.com replacment which does not use this pin, but I am leary. Also, the trigger guard would need to come off, and this seems way hard on the Mak - I have the right instructions, but so far - no go. This gun WOULD require to have the barrel covered. I would also have to cover the FEEDRAMP and chamber. I was going to use duck tape wrapped around the barrel double to triple thick. The blast guy did mention silicon plugs.
The complexity involved has me almost ready to punt and go with a bead blast and cold blue. Of course the PreB is totally stripped and shouldn't be that hard to blast. My concern is those guys blasting too much or too much inside the frame. It is just that I cannot get small quantities of Al Oxide in 120 MESH, and I figure people who blast for a living know how to prep a surface better than me.
BTW: I plane to use an el cheapo external mix air brush from Harbor freight. it has a stainless and brass tip, and looks as good as the badger external mix. It runs on canned air. If this does not work, I may spring for the $80 Badger internal mix. If I was definitely going my Mak, I wouldn't mind, but I don't want a one gun money pit...
June 29, 2005, 12:25 AM
The best thing I can tell you is if you cannot completely strip the Mak, don't try to blast it and then park it as one unit. The oil and grease left on the internals will kill the parking solutiion. The duct tape will be very hard to get off if you leave it on the metal for any length of time. I would stay away from it with guns. The blast man should have the blasting tape. As to the pin for the sight base, get a cheapo set and turn one down if you need to. Mount it in a drill and use some sand paper to reduce the size until it fits the hole the pin lives in. Make sure the pin drives out and doesn't have an end that has an enlarged head to hold it in. If it does, it should drive out right to left, but it may be truned around from the other side which will not let it drive out correctly. Good luck,
June 29, 2005, 05:45 PM
Seems like a lot of trouble to go to for an $80.00 gun. Have fun! And good luck.
July 2, 2005, 11:24 AM
A couple of odds and ends to throw in:
Cntryboy's description of using rust inhibitor post-blasting for a delay in getting to the Parkerizing operation is a good idea. This is one of the few occasions when Water Displacing formula number 40 (WD-40) is actually good for something. It was developed as missile part rust preventive originally. It is thin, so it is removed relatively easily, and if there was any trace of water in the blast air, this will get it off the surface microscopically.
Any time after spraying with WD-40, drop the parts into ordinary mineral spirits to remove it. This not only removes WD-40, it evaporates off afterward. Kerosene is a more flammable alternative. A five minute dip in acetone after most of the mineral spirits or kerosene dries, will remove the last traces of it and WD-40. Acetone will also remove water by dissolving it. In college chemistry class I remember we used it to dry water out of cleaned glassware.
Do not go straight to the Parkerizing tank with acetone, MEK, alcohol or other volatile solvent still on the metal. Acids react with some of these. Instead, drop the parts in boiling distilled or de-ionized water. That not only removes solvent traces, but if any WD-40 got trapped in a crack or recess, the heat and expansion and bubbles will drive it out. If you see anything floating on the water surface, you know you didn't get it all off and need to repeat the acetone dip. You will also need to clean out the boiling vessel and put fresh water in for repeating the boil afteward.
The other purpose the boiling serves is that any microscopic trace of ferric oxide (red rust) that has formed because of condensation when the solvent evaporated will be converted to ferrous oxide (blue rust; this is the basis of the rust bluing process). The boiled part not only dries fast, but the heat in the presence of air (and really hot tap water does this too) forms a thin layer of the blue oxide that helps inhibit rust for a few hours if you can't get straight to the Parkerizing tank. The acid in the Parkerizing solution removes the ferrous oxide instantly, so it doesn't affect the Park-bath.
July 3, 2005, 10:17 AM
I have bead blasted and parkerized two guns now. I stripped off or removed only the parts that I didn't want parkerized. Bead blasted the guns. Then put them is a solution of boiling water and rubbing alcolhol (80 water to 20 alc) for 30 minutes. Removed them from the boiling solution and washed and rinsed them thoroughly with liquid soap under hot running water.
Then put them in the parkerizing solution. Both of them came out with excellent parkerized finishes - imho.
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