Proper use and application of MEK

[TroyW]

I'm working on my practice kit, and will be using the Sherwin Williams 988 GBP primer. I'm getting ready to clean and prime the stiffeners in the airfoil section, but can't find a reference on how to use the MEK to clean the alumimum.

Dan Checkoway's site has a great page with pictures; he suggests using a spray bottle to spray it on the part, scrub the "bejeesus" (his words) out of it with a scotch-brite pad, rinse it with water, hang it up to dry, then prime it when it's dry.

Is that what you all do? I was wondering if I could keep some MEK in a large container (wash basin with a sealed lid) to use to submerse/wash/scrub the parts--would that put enough contaminants in the MEK to render it unusable?

Just curious what you all suggest...

Troy Whistman
Fort Worth, TX
Build blog: www.whistman.com

[jcoloccia]

I wouldn't want to be in the same room with a uncovered bucket of MEK and I wouldn't want to be in the same state with that stuff misting around out of a spray bottle . It's absolutely nasty except in small quantities where it's merely noxious

I don't want to talk for him, but I've got to think he's spraying Metal Prep, not MEK. Personally, I just wipe down my parts with some MEK, Acetone or Laquer thinner (whatever I'm in the mood for that day), and spray. Some people use Dawn and warm water.

This has been working for me, but I'm also kinda' curious what other people are doing. The whole metal prep, scrub, alodine, epoxy thing's been done to death, but I haven't read much on prepping before rattle can stuff. Like I said, I just wipe it clean with no scrubing and it appears to stick like the dickens, whatever THAT means.

[rzbill]

I too, simply use an MEK paper towel for a final wipe down. No comments on primer prep. That is covered elsewhere. I would not recommend a large open container of MEK. It evaporates very fast and is flamable. When wiping down a part or two, I usually don't bother with a breathing filter. However, when doing my tanks and cleaning cleco's afterwards, I learned to use the filter mask. I skipped it for the first two session and noticed some bronchial irritation afterwards (the next day). It was just a matter of having my face in the stuff for a long time. The filter mask cured it. I wore it while cleaning cleco's not while dancing with the proseal.

[TroyW]

Originally Posted by rzbill

I too, simply use an MEK paper towel for a final wipe down. No comments on primer prep. That is covered elsewhere. I would not recommend a large open container of MEK. It evaporates very fast and is flamable. When wiping down a part or two, I usually don't bother with a breathing filter. However, when doing my tanks and cleaning cleco's afterwards, I learned to use the filter mask. I skipped it for the first two session and noticed some bronchial irritation afterwards (the next day). It was just a matter of having my face in the stuff for a long time. The filter mask cured it. I wore it while cleaning cleco's not while dancing with the proseal.

Thank you both for your comments. rzbill, you say "use an MEK paper towel"; is this just a normal paper towel soaked in MEK, or something special?

Also, will MEK remove finger oils, etc., or is there a need to wash with Dawn and water first, then MEK wipe before spraying?

Do you rinse with water after the MEK, or just let it evaporate?

Amazing how hard it is to find this "basic" info! I couldn't find a thread with the answers, so figured I'd start one!

[TroyW]

Originally Posted by jcoloccia

I don't want to talk for him, but I've got to think he's spraying Metal Prep, not MEK.

Oops, you're right, sorry Dan! It's AlumiPrep he's spraying, not MEK.

I noticed the MEK takes the sharpie marks right off the metal. Van's instructions say do not EVER scribe or punch the metal to mark it. So what do you do to keep the sharpie 'orientation' marks for reassembly? Do you clean the metal then immediately re-write your marks?

[jcoloccia]

Originally Posted by TroyW

Also, will MEK remove finger oils, etc., or is there a need to wash with Dawn and water first, then MEK wipe before spraying?

MEK will pretty much take everything off of anything. Acetone works nearly as well...maybe better since it doesn't evaporate as fast so it's easier to work with. I personally like acetone better...not as noxious. I happen to have a can of MEK lying around so I'm using that. These are the solvents I happen to have experience with through work and it's my comfort zone. YMMV. Priming is a hotly debated topic....check out the neverending debates. Just to give you an idea, do a google search on:

"what kind of primer to use"

The very first link is to www.vansairforce.com (no, I'm not kidding )

I'll also say ignore anything I say and chalk it up to it's just what one schmuck trying to build a plane happens to be doing. Also, I've switched primers 4 times looking for a good balance of "easy" and "warm fuzzies". Hey, I'm allowed.

Originally Posted by TroyW

Do you rinse with water after the MEK, or just let it evaporate?

Good luck trying to make a puddle of MEK. By the time you get the ball loose in the can of 988, the MEK is halfway to China. Acetone evaporates a bit slower....it only makes it to California.

Originally Posted by TroyW

I noticed the MEK takes the sharpie marks right off the metal. Van's instructions say do not EVER scribe or punch the metal to mark it. So what do you do to keep the sharpie 'orientation' marks for reassembly? Do you clean the metal then immediately re-write your marks?

Actually, somewhere in there he says it's okay to use light punch marks or an engraving tool (very light marks with the engraving tool). Maybe not in the instructions for the practice kit, but he says it in the preview plans/instructions for the real deal. I tried using punches on some scrap, but I don't have a light enough touch with the hammer....lol....wasn't pretty) So I use the engraving tool. This was back when I was MetalPrepping because it was totally inconvenient to wash the parts with water, dry off a little bit and remark with the sharpie (doesn't seem like a lot of work, but just try to do this dripping wet wearing goggles, a respirator full of snot, and heavy chemical gloves). Now that I'm just wiping with Acetone (or whatever) I'll probably just remark them as I wipe them off.

Some guys have come up with some pretty cool marking systems using pieces of wire stuck through rivet holes, or laying things out a certain way when they prime. Search through these boards and on the net. Lots of really clever people out there.

[rv9aviator]

I used the hot water (Dawn) scrubdown with scotchbrite, let dry, wipe (no lint paper towel) with your favorite carcinogen (MEK, acetone) and spray with whatever self etching primer (my second favorite carcinogen) P-60 or 988. The P-60 stuck like glue and the rattle cans did OK.

[Red]

I use the PPG automotive line except for the primer. The process that I use is a wipedown with Wax and Grease Remover (DX330), Aluminum cleaner (DX533, acid etch), Aluminum conditioner (DX503, alodine), prime with PPG Super Koropon.

Super Koropon is a very good fluid resistant primer used by the military and commercial airplane builders. I have wiped down cured primer with various paint solvents, MEK, acetone... nothing I have found so far affects the cured primer. It is also less expensive than what I could get the PPG automotive epoxy primer (DX50) locally.

[TroyW]

Originally Posted by jcoloccia

Actually, somewhere in there he says it's okay to use light punch marks or an engraving tool (very light marks with the engraving tool). Maybe not in the instructions for the practice kit, but he says it in the preview plans/instructions for the real deal.

I was looking at section 5C of the instructions, titled "MARKING PARTS". He says, and I quote:

Originally Posted by Vans

NEVER use a scribe to make layout lines or other marks on aircraft parts. The lines can cause failure of the part along the lines with the vibration of the engine. The use of an ordinary lead pencil will cause corrosion of the aluminum. We recommend that you use only an extra fine point "Sharpie" pen. For some unexplaiend reason the blue ones seem to last longer than other colors. The sharpie ink will bleed through primer, so you can still see the ID marks after priming the parts.

[TroyW]

Dang, these could be convenient!

http://www.aerocraftparts.com/ItemFo...x?item=KSW0107