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OHW vs Primer vs AP

smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭
In a different thread, the past couple of days was some discussion about OHW vs 2k primer vs AP.

And I just happen to run into this situation.

I wanted to make a new thread though, the other one is way off topic

( http://k2forums.com/discussion/12292/ar-build-and-dip/p4 )



Not really...OHW is more costly than my NanoChem or Hydrosolutions...According to the adhesion tests we have done? Epoxy has better adhesion and THAT is the name of the game...

Price of OHW is too expensive for us to justify using it for production. We love it for small jobs in odd colors.

it's much cheaper to do a coat of NanoChem AP (about $30/gal) and coat of Aqualac (about $40/gal). AP takes literally seconds to dry. One guy coats a rack of parts w/ AP and it goes directly to the painter. Both are sprayed from pressure pots, so it's not like we are using the same gun and having to clean in between. I would honestly leave AP in a gun all the time like activator if we didn't have a pressure pot.

Yeah, I was always baffled why people make such a big deal out of spraying AP. leave it in the gun and dust it on while you are prepping the work. We times it, and it literally adds SECONDS to your process... even with large runs of parts. We looked at it as waterbased was so much easier to use that it was worth it.

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Long read, but the background is important...



So, those PP welding helmets I've been doing. The guys business is slowly growing. I'm his "dipper". We have both learned a lot about processing this type of plastic.

The first helmet i did for him was a "tester" helmet. I used 2k epoxy primer, nanochem paint, express clear. We could NOT get the finished product to "fail". Forget normal adhesion test..we drilled holes thru it, cut chunks out of it, dug "groves" into it....

Although his business is growing, it's not really production. And the "painted" portion of his business sells less than his non-painted portion. A "wow that's cool!" vs "wow, that's more expensive!"

Sometimes weeks he may not sell any dipped ones, some weeks one, some weeks 3 or 4.

The designs he sells more of, we will make 2 or 3 at once, just so he has them on hand and ready to go (important fact).

So, for actual use, I switched to OHW. When doing just one or two helmets, it's just easier to pick up that PPS cup already full of OHW instead of mixing up a small amount of primer (man, that stuff is messsssy!).


This past weekend, we found that OHW does NOT have the same adhesion as the primer. He was re-doing some of the work he does on the finished product, when a small portion of the edge of the paint/clear pulled off. He gets aggressive with rivets/very powerful glue, and was removing some previous stuff.

So Friday night, we got together and tested things. A fully finished PP plastic piece, done with OHW and express clear, when we did a cross hatch test using duct tape, it WILL pull that area (and a bit more) off the helmet.

Now, duct tape is super duper strong. So we tested also with some 3M automotive masking tape I have, and it lifted a really small area, but it still lifted.

Using blue painters tape did nothing.

We tested several different helmets, done at different times, to make sure it was not a specific "batch" that had an issue. Every single one had same result.


I prepped one and used some 2k epoxy primer, then we went and had a few drinks while it dried. No dip or clear, just primer....and that primer would not come off.

This surprised us both. OHW is suppose to stick to plastic. That's why I use it.

----


Real life Usage..

He's got a couple of dipped welding helmets that he personally wears. Several of his friends have one. They have been wearing/using them daily for months now. Zero in the field issues with the OHW ones.

The cross-hatch with duct tape and 3M masking tape was an "in lab experiment". Not every day "real life". But.. it still failed. And like @K2Concepts said, it's about getting the BEST product out there.. not the "this will do" product.



-----

More testing required...

I wonder if maybe, even though I'm blasting the parts, maybe it's not enough. Maybe it needs more for the OHW to bite.

The parts are also textured. Almost but not quite dimpled. I've wondered if maybe that could affect a cross hatch test.

I've got a lot of testing to do. He brought over about 20 "scrap" pieces from when he modifies the helmet.

I'm going to blast a part, then scuff it to put scratches in it, see if that changes the test results.

I've never used an adhesion promoter before. After reading what @MidOhioHydrographics and @WileECoyote , maybe I should go that route.


---

(I can really be long winded in some of these threads...)

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Comments

  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    I would also suggest using OHW topcoat if you're using OHW paint. Jason @onehitwonder can't guarantee his paint compatibility under other clears. There's a reason most paint systems are "systems" where the products are designed to work together.

    Adhesion testing/cross hatch testing needs to be one of the first things you do when doing multiple parts for a company. Find the least expensive way to get the best adhesion. We don't even blast our polypropylene parts. We degrease in our parts washer, blow dry, apply NanoChem adhesion promoter, Prime Coatings Aqualac paint, then topcoat with either Prime Coatings Diamond Matte clear, NanoChem 0-1% Deet Resistant Clear, and sometimes NanoChem UV Resistant clear.

    If we have a failed dip (so no topcoat applied) and we try to blast the paint off? We will deform the plastic before the paint adhesion fails. Pretty incredible.
  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭
    @MidOhioHydrographics

    You don't even blast them?

    I'm going to order some nanochem AP today.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    Correct. We do too many parts to blast each one. Light coat w/ the AP, barely wet it. We use a 1.3. Think "dusting a coat". It will literally flash off before your eyes.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    I should note, HDPE does not work like that. We must flame/blast/hit with gamma rays.... something to get proper adhesion there. PP works great.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    Also, not all PP is created equal. There is variability on the grade: all virgin material, some regrind, all regrind, etc. So just test everything.
  • Fejery4491Fejery4491 Posts: 133Member ✭✭✭
    @smedlin I was watching that discussion on the other thread pretty closely too. I'm glad you started a seperate thread for it.

    We probably use OHW on 80% of the work we do. We've had small amounts of issues on plastic parts, mainly HDPE.....most often than not it hasn't been an issue with flame treating for us, rather surface prep. Lightly stuffing the part doesn't seem to give it the bite we need with OHW.....but if we get more aggressive with it, say 320-400 sandpaper.....it sticks like crazy. But then the plastic gets raised scratches and we almost always have to lightly sand the high spots off the first one or two coats and throw one more on agree.

    Makes me want to try an epoxy primer and/or AP since I could save alot of time sanding....and still potentially get the paint to stick good.

    Guys say you can just leave AP in the gun, so for guys who don't do a TON of parts couldn't a guy just leave a PPS cup full of AP....spray the AP....and quickly run some acetone through the gun and swap to your base? That wouldn't hardly add any time to the process.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator



    Guys say you can just leave AP in the gun, so for guys who don't do a TON of parts couldn't a guy just leave a PPS cup full of AP....spray the AP....and quickly run some acetone through the gun and swap to your base? That wouldn't hardly add any time to the process.

    Yep. I would say that would be just fine.
  • WileECoyoteWileECoyote Posts: 6,164Member, Moderator, Business Ninja El Moderator
    @smedlin The Prime coatings PolyPro Primer is no joke... its the best AP we ever used, and you just DUST it on all surfaces.

    Keep this in mind too, just a general rule. Give the customer what he PAYS for. If you cut 20 minutes out of your process by using OHW and the paint sticks good enough (what the customer will pay for) then that is your best option. Even if you can get the other paint to hook up better, but it costs you in time. (Your results vary on your process)

    @Fejery4491 When we had slow times, we would rinse our AP gun and PPS cup out at the end of the night after dumping the remainder back in the container. Honestly, take your first activator (harbor freight, home depot special gun) and use that... the atomization isn't that important.

    And we always use the strongest tape we can find for our crosshatch testing and always do it the same. See my comments here...
    http://k2forums.com/discussion/comment/70615#Comment_70615

  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭



    We probably use OHW on 80% of the work we do. . Lightly stuffing the part doesn't seem to give it the bite we need with OHW.....but if we get more aggressive with it, say 320-400 sandpaper.....it sticks like crazy. But then the plastic gets raised scratches and we almost always have to lightly sand the high spots off the first one or two coats and throw one more on agree.

    Makes me want to try an epoxy primer and/or AP since I could save alot of time sanding....and still potentially get the paint to stick good.

    that's matches up exactly with what I was telling the client (welder helmet guy). It's almost like the surface, even after blasting, is to smooth for OHW to bite. However, just like you said, if I scratch it with abrasive sand paper, you can feel it after you paint. Which is why I wanna try scuffing it with a red scotch pad.

    But.. if a good AP solves the problem? Then I could use nanochem paint, which is cheaper. (I keep both OHW and nanochem on hand).

    And not have to even blast??

    Just degrease, mist with AP, and paint??

    Anyways, I ordered a gallon of nanochem AP. I'll do some testing and see how it turns out.

    .


  • loochlooch Posts: 1,672Member ✭✭✭✭✭
    Can the adhesion promoter be used with ohw or would that cause problems @WileECoyote
  • K2ConceptsK2Concepts Posts: 13,066Administrator El Jefe
    @smedlin Yea brother you are going to like that stuff...
  • DeviousDipsDeviousDips Posts: 1,583Member ✭✭✭✭
    Nanochem AP works great. Big fan of nanochem products. Their epoxy primer is some tough stuff as well
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    looch said:

    Can the adhesion promoter be used with ohw or would that cause problems @WileECoyote

    No reason to.
  • WileECoyoteWileECoyote Posts: 6,164Member, Moderator, Business Ninja El Moderator
    looch said:

    Can the adhesion promoter be used with ohw or would that cause problems @WileECoyote

    I doubt it would cause problems, but its an unnecessary step, that probably doesn't help at all (it's not like you are going to get SUPER adhesion), its wasted time and money, and its bad practice to deviate from the manufacturers direction.
  • onehitwonderonehitwonder Posts: 2,706Member, Business Ninja ✭✭✭✭✭
    We designed OHW to go to every surface, and cut out steps and material, such as Ad Pro and primer. Our parts for Kia production we’re almost all PP or ABS, and we’re vigorously tested for adhesion, with zero failure. That said, there are a lot of different parts and plastics out there, and besides HDPE, nothing’s needed flaming. For adhesion TESTING however, we recommend at least 12 hours, to let OHW do its job, as there are no hardeners or ad pros involved.
  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭
    I watched a few videos on you-tube, about spraying AP.

    To me, it looked like they were treating just like paint. Not "misting" it, but spraying just like paint.
  • onehitwonderonehitwonder Posts: 2,706Member, Business Ninja ✭✭✭✭✭
    It should be a light coat, and it has a 4-5 minute window
  • WileECoyoteWileECoyote Posts: 6,164Member, Moderator, Business Ninja El Moderator
    @smedlin Different products work differently. The Information about Prime Coatings Poly Pro Primer is directly from one of the Lab techs. Other versions I cannot speak too.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    I should note... We tested OHW on our Polypropylene parts and adhesion was just as good as AP + Aqualac. Cost was the reason we couldn't use it in production. (not adhesion/durability)
  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭

    I should note... We tested OHW on our Polypropylene parts and adhesion was just as good as AP + Aqualac. Cost was the reason we couldn't use it in production. (not adhesion/durability)

    I really think the problem I'm having is the same as @Fejery4491 is having; even after blasting, there just isn't enough for OHW to bite into.

    Not knocking OHW. It's the parts i'm dealing with.

    That really intrigues me. You can tell the part has been blasted. It' all "dull" instead of shiny.

    I wonder if the material is to soft? If I turned the pressure on the cabinet down, would it actually do a BETTER job of etching this stuff? May have to try that when I get home...


    Hopefully using AP will give a better result. The other option is to just go ahead and use epoxy primer.
  • Fejery4491Fejery4491 Posts: 133Member ✭✭✭
    @WileECoyote I think the only cheap gun I have around the shop is like a $25 1.8.....wouldnt that be too big for AP?
  • WileECoyoteWileECoyote Posts: 6,164Member, Moderator, Business Ninja El Moderator
    The tip size just dictates the size of the stream, which gives you a guess as to how much air is needed to atomize completely. The fact that AP is not very viscous helps that happen. Your pattern is going to be a bit bigger than what is needed, but its not going to hurt anything. Probably just cost you a little in material.

    Of course you could always go break the bank and get another $25 gun with a 1.2 nozzle in it from Home Depot or something...
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    Quick question @smedlin ... are you still using glass beads? Or have you switched to aluminum oxide for blasting???

    We didn't blast the PP and OHW still stuck fine in our tests. Not sure why you're having issues. Again, not all plastics are created equal. May be a different grade
  • K2ConceptsK2Concepts Posts: 13,066Administrator El Jefe
    AO or Garnet...I prefer Garnet...MUCH less messy and it won't break off and embed into the material like AO...something to think about...
  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭
  • K2ConceptsK2Concepts Posts: 13,066Administrator El Jefe
    edited May 16
    smedlin said:

    @K2Concepts using glass beads

    @smedlin



    OK well there is your problem...glass beads will only dimple the surface, not unlike a golf ball...you should only use glass bead for rust removal or polishing...AO or Garnet will leave a profile or crater...looks like an upside down piece of broccoli or cauliflower...so your paint or primer has a toehold into the material...

    You guys need to start reading more on the forum before you start blasting away and then get poor results...and besides...I think I went over this int he training...or maybe not...your off the hook for this one...
  • WileECoyoteWileECoyote Posts: 6,164Member, Moderator, Business Ninja El Moderator
    Yeah, sorry @smedlin you gotta get a better profile than glass is gonna give you on that. 
  • smedlinsmedlin Posts: 1,741Member, Business Ninja ✭✭✭✭✭
    Well, at least we found a (probable) reason.

    Looks like i'm going to order some Garnet.

    I did get the AP in today. I'll test that method. Would be nice if I don't even have to blast it.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    edited May 17
    I've been saying this for a very long time, and I know Sean and Dinnetta use glass beads... (and people say glass beads aren't necessarily "round" but you can find photos to support and contradict that), Either way... AO creates the best possible profile on everything. I've seen glass beads just polish, almost make shiny, the surface of some steel (hardened tool steel, but you should never encounter that to be dipped. We had a Cerakote job.) But why compromise when AO etches damn near everything amazingly well and it's relatively cheap! Especially when you consider how many times it can be reused. Get 80-100 grit AO and blast at a lower pressure for plastic. It won't chew it up. We do it allllllll the time. Any custom job that comes in (plastic, metal, existing coatings) if it fits in the cabinet, we blast. Period. Why risk it? I'm not sure exactly what glass beads would do to PP on a microscopic level. I don't have any way to see it. But I do know AO works on everything.

    Garnet or AO, whichever you can most easily get. Both cut well. But get good, clean media. The stuff from harbor freight would be ok to test with, but it's dirty has hell. Avoid it if possible. I get my media from a blasting company in Ohio (http://www.stanley-industries.com). Cost is $0.63/lb, flat $75 shipping per pallet so I get like 500-700lbs at a time. I've heard people say Zoro is good. But $68.54/50lbs is expensive even w/ free shipping.
    https://www.zoro.com/zoro-select-blast-media-aluminum-oxide-100-grit-aob100-50/i/G2968472/


    Sean and Dinnetta at Big Brain swear by glass beads. They've found a system that works for them, I just don't agree with that media for the purpose of etching for paint adhesion. To each their own, but why compromise? Use something you know will cut. AO really isn't very dirty. Cerakote recommends it for all their prep just for the dimple vs cut reason. Adhesion is adhesion regardless of what you're spraying.

    Ok, rant over. LOL
  • MidOhioHydrographicsMidOhioHydrographics Posts: 9,205Member, Moderator, Business Ninja El Moderator
    edited May 17

    AO or Garnet...I prefer Garnet...MUCH less messy and it won't break off and embed into the material like AO...something to think about...

    I may have to try Garnet. What's cost comparison? For our purpose the AO works very well, but I also haven't tested Garnet. May give it a shot.

    Also, good article here:
    https://mediablast.com/blog/2016/04/28/which-abrasive-to-use/

    First paragraph:
    "The two basic types of abrasives are cutting and non-cutting abrasive. Glass beads, plastic, soda and even steel shot are considered non-cutting abrasives. Glass beads are by far the most used non-cutting abrasive type being that they do not reduce the size of a part and remove only the surface coating be it paint, rust, etc. When used correctly, glass beads can actually make the size of a part appear to grow by making a small crater in the part surface that measures larger unless you are using a profilometer, a measuring instrument used to measure a surface’s profile, in order to quantify its roughness. When used properly, glass beads impact the surface while spinning, making a small indentation in the part surface and sealing the surface. In some cases, depending on the part material, the surface is sealed with a luster. The larger the bead the more luster the part has after blasting."


    @K2Concepts where did you get your aluminum oxide?

    Also found this in the same article:
    "One important factor to always keep in mind is that blasting cabinets use different kinds of abrasive than portable blast equipment because the later doesn’t recycle abrasive. For example, softer much less expensive cutting abrasives like sand, slag and garnet should never be used in cabinets because these abrasives will overload any size dust collector and quickly create a huge mess."

    Thoughts on this? Seems like it may break down more quickly?

    Also a good chart here, but no mention of Garnet. Notice the Glass bead says "No Etch"
    http://www.kramerindustriesonline.com/finishing-guides/blasting-media-comparison-chart.htm

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