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Posted: 5/8/2008 5:46:05 AM EDT
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Well I gunkoted my Saiga and finish looks beautiful but it chirps very easily. What the problem? I followed this procedure to gunkote the gun. 1. I sanded all parts with 120 grit sand paper (I don't have access to the blaster), what I couldn't get with the sand paper I used a drammel with sanding attachment. Cleaned up all the parts, and all external surfaces. 2. I then degreased it using brake cleaner from Pepboys. 3. Then warmed up all parts to about 120 f for about 10min. 4. I then started coating all parts part by part (if next part in line would get cold I would reheat it again). 5. Then I gave about 30 mins for the parts to dry, and put them in the preheated oven for little over an hour at 315 f. I didn't touch any parts, nor they contacted anything before baking. When parts got cooled I assembled everything and noticed that finish comes off very easily. Please let me know what I did wrong, or maybe next time I should use some other finish. |
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The first thing I started seeing flacking is the top of bolt carrier (the part that rides under the dust cover). The gun was pretty dry(no oil) before I even started to sand, and after sanding it shouldn't have any oil, its weird. Plus when I degreased it I dumped the whole 1lb can on it. I guess I will have to redo it again. It sucks as it takes a lot of time to sand it all down. Thanks. |
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If that is the only spot, that tells you its rubbing, probably inside the rear sight frame. Look for the friction point, before you recoat, or you'll see it again (based on the description & w/o seeing the actual wear.) I wore some nice shiny spots on a mix-match kit, where the BC and a spur on the dust-cover were making contact. 
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Likely a friction point - though it's also a good idea to PREBAKE the barreled action for about 30 minutes at 250F once you think it's "clean". This often causes all SORTS of crap grease to bubble out :) You should have seen some of the Romanians that I thought were clean :) A note on this.... "put them in the preheated oven for little over an hour at 315 f" Not quite right :) Preheating the OVEN doesn't preheat the GUN PARTS. You want to load your oven cold, THEN fire it up. Watch for the light to go off, and start timing from THAT point. I usually go 1 hour 10 minutes at 350F ... just a WEE bit longer & hotter. Many ovens cook a little "cold" - but DON'T overdo this. |
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Thanks for the replys guys. The flaking is not on rubbing points, but ectual flaking When I said little over an hour I meant about 1:30min, the oven is also one of the newer digital once and the temp was set at 315 f. So it shouldn't have been lower than 300f. But I got the point, next time I will degrease it much much better and cook it a few times in the oven before I start coating, and will cook on higher temp when coated. Thank you guys!!! |
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I feel your problem came from useing brake cleaner. Have had it happen to me as well. It does leave a light "film" on the surface. Use MEK (methyl ethyl ketone ) as your degreaser. I also use a propane torch to heat up around gas block/FSB to get any oils out as well. 3-4 cleanings in the MEK,and your ready to top coat. |
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How heavy are applying the GC? It is not like spray paint. The thinner you apply it the more durable it is. That's why air brushes and small HVLP spray guns are good for applying it. I have also found that applying it thinly over park is more durable than over bare steel. GC and park really work well together. |
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PETman has a point - I should have read more carefully. I use Brake Cleaner as well - but just for my INITIAL degrease. Once I've done the first cleaning, prebaked, and done a followup clean with Brake Cleaner? I always sit down with new white gunrags & a can of Acetone. By hand, I go over every part & the barreled action to do a final Acetone wash. |
| Put your metal parts in the dishwasher first. Use the powdered detergent, then after you remove the parts, use a blue torch on the parts to sizzle off any water and to open the pores. While the metal is hot to the touch, spray on the gunkote, let sit for a couple minutes, then put in oven. |
Something you should know is that the can stuff sucks. For example, I did my romy G with teflon moly using the thinner/moly mix through an airbrush. On the back of the can it says to start with 1 part thinner to 4 parts teflon. That's total bullshit though. We all mix 50/50 here, so it gets into the sandblasted pores easily. Another thing to consider is that you're heating it in the oven. Why do that? Once you spary it on, it won't have time to go into the pores because it hardens right away. I know, you're thinking the opposite will happen since the heat would make it flow, but that's not the case since heat makes it harden faster. Nowhere does it say to heat the parts OVER room temp. If the parts are cold, then heat them a bit. And yes, grease is a bitch. I experience cracking too around the areas such as the pin. When you fire a romy-G even after cleaning it, the heat get's out all the old cosmoline. There is TONS in there. |
Yup, add gun parts to oven then turn on! |
Eh, why not use just cheap Acetone? That's what we all use here. What's the point of all those expensive products? They'll give you cancer. |
Why do you say when metal is hot? It just seems counter productive to me. You want it to go into the pores, and it can't do this if it dries prematurely. |
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omega53513, I will see if I can shead a little light on your problem. But first of I should say I have never used Gunkote before, I'm got a big fan of any type of paint in a spray can for this type of application. They are a "single part" paint, there is only paint and propelant in the can. You are much better off using something like DuraCoat which is "two part" paint. Two part refers to 1)paint 2)activator/hardener. Two part paints cure through a chemical reaction, single part paints dry through evaporation. Notice I said one "cures" and the other one "dries". When a two part paint cures it will stick to the surface much better, last much longer and be resistant to chemicals. I personally have no clue why paints like Gunkote and DuraBake aside from speeding up drying time. The main reason in the autobody/painting industry we use bake ovens, is to speed up production time. Even when the finish is baked, it is not cured. You bake it to get it out the door faster, plain and simple. It takes 3-4 weeks for paints to fully cure, it has to release solvents. But all that doesn't really explain the problems you are having. Unless I missed something in your post, it sounds like you applied the paint right over bare metal. There are DMT(direct to metal) out on the market, but I would be every leary of any paint in a spray can that makes that claim. At the very minuim, you need to apply a metal etching primer before apply your topcoat. Any autobody supply place should carry this, even better is a two part zinc based metal etching primer. The two main things that set off red flags for me are the following...applying paint over bare metal and using brake cleaner to degrease. For degrasing there are several, the best would be a autobody type degreaser. Otherwise laquer thinner or acetone will work better. To me it sounds more like you are having an adhesion problem, you might also be running into some contamination. But typically paint flaking is from bad adhesion. kingfish, I would highly recommend you DO NOT put parts in a dishwasher to clean them. Bare metal doesn't like water. Even if you ran straight from the dishwasher to torch to paint, the surface has already started to rust. You may not be able to see it with the naked eye, but there is rust already started. Then you cover it up with paint, this accelerates the rusting process. Which then leads to paint failure. There are a number of things in this thread by a number of people which is simply bad advice when it comes to painting. I am just getting into gun building myself, but one thing I know about is painting. I have been in the autobody/painting for over twenty years and most of my years have been on the painting end. If anyone is interested, I will do a turtorial on painting. It would be a few weeks off, I'm hosting an AK build party next weekend. So time is too limited this week to start one now. Don |
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