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SCOTTRODS, thanks for taking the time to post this info. Hopefully somebody will be close to your area to throw some business your way.

A friend of mine was dissing the local powdercoater for not using a Phosphate wash, after blasting, prior to powder.
How important is that?

Also, the local powdercoat guy was saying that i was wasting my time by bead blasting the parts myself beforehand.
If i would have brought him the parts still painted (but clean) he would have charged me the same.
Says that he has to do them completely again anyway, so no money saved...

His work looks good, has lasted a long time, and he masks off the threaded holes and stuff well.

Still, I'm suspicious...
Any pros out there got an answer to these?

Clatter wrote:A friend of mine was dissing the local powdercoater for not using a Phosphate wash, after blasting, prior to powder.
How important is that?

Also, the local powdercoat guy was saying that i was wasting my time by bead blasting the parts myself beforehand.
If i would have brought him the parts still painted (but clean) he would have charged me the same.
Says that he has to do them completely again anyway, so no money saved...

His work looks good, has lasted a long time, and he masks off the threaded holes and stuff well.

Still, I'm suspicious...
Any pros out there got an answer to these?

As Far as Iron Phosphate, or conversion chemicals, They were originally used as a way to avoid Media blasting parts that would be going on a Line coating system. Blasting is a huge labor cost item, and eliminating it, companies saved a massive amount using automated chemical conversion systems, including heated, spray-on, and rinse systems.... not many people needed and it is a FAST solution for production parts.

Blasting, is just like sanding any other type of material for coating, with wet paint systems or one of many other types of finishes.... It provides a "tooth" for the finish to grip. That being said, this is one of the purposes for the phosphating,... it does indeed promote adhesion, however, it also provides added corrosion resistance to a coating process, where Blasting alone does not.

The need for the conversion stuff, is truly based on the application of the coated part. If I were living in a coastal area, everything I coat would get a conversion treatment AND blasting, but in the reverse order.... Blast first, chemical conversion afterward, as the chemical treatment will also rinse off any dust and fines left over from the blasting process. I don't use any conversion treatments and have some parts that get abused pretty heavily and still are holding up after more than 3 years.... almost 4. Some of the stuff looks as though I coated it yesterday..... some is worn, due to extreme use, such as ATV foot pegs, where abrasive dirt on the bottoms of the shoos/boots, is the enemy. No way around wear on those types of parts.

You can also use a corrosion resistant primer powder before a color coat, similar to wet paint systems. Generally, there are two types of primers. Epoxy primers, that can be used in any application, and ZINC RICH primers to be used ONLY ON STEEL or ferrous parts. That last sentence is VERY important, hence the caps. Using a zinc rich primer on an aluminum part will CAUSE corrosion under the powder coating, and certain failure is in order shortly down the road.

So, in short, Phosphating is a good thing. It's not completely necessary on all parts (or in all processes), but does aid in corrosion prevention or slows down corrosion if the coating is compromised (where if it's gouged from some active issue, you'll want to get it re-coated anyway) and it aids in promoting adhesion, long term.

Phosphating is argued over all the time in the custom coating forums. Some say it's a sales pitch, others stand by it as gospel.... I say it's got its place..... just not every place.

Now, as far as bead blasting, I would love it if everyone I did parts for would bring me clean, bead blasted parts. I'd still blast them with an appropriate media so I KNOW that it's done right. If I don't I can't guarantee my work at all. Bottom line, is you're wasting your time, unless some friend of your is doing the coating and doesn't have the means to blast. If you're going to do that scenario, get some 80 grit Aluminum oxide to blast them with, It provides a better "tooth" where glass bead actually dimples, or "polishes" the surface leaving a less than desirable surface for the powder to adhere to.

I don't give any discounts for the customer having "prepped" his own stuff.... I still have to treat it like it's just a clean part, and start from the beginning.... So yeah,... in essence, you could say it's a waste of time, but I'd love to have you as a customer....

is the water muddier now?

After reading the rust thread,
I can't help but want to wash down my freshly coated parts with some Ospho...

This should get in all of the cracks, and convert the rust.
Places where the coating can't reach...

But would it hurt the powdercoat in any way?

I can't suggest a phosphate wash to my local powdercoater.
He already knows everything.
Anything that is not his idea is wrong.
(you know the type...)

Thanks for the wisdom.. It really, really helps.
SO many times you have to learn to do every single stage of the process because there are so many slacks out there.
(Especially in CA)

Clatter wrote:After reading the rust thread,
I can't help but want to wash down my freshly coated parts with some Ospho...

This should get in all of the cracks, and convert the rust.
Places where the coating can't reach...

But would it hurt the powdercoat in any way?

I can't suggest a phosphate wash to my local powdercoater.
He already knows everything.
Anything that is not his idea is wrong.
(you know the type...)

Thanks for the wisdom.. It really, really helps.
SO many times you have to learn to do every single stage of the process because there are so many slacks out there.
(Especially in CA)

I couldn't tell you about the "Ospho", but I can tell you,.... if you wouldn't wash your kids hands with it,.... don't put it on the powder coated parts. PC is pretty robust, but it still has it's Kryptonites.... Most solvents are no good for powder. The one thing I have had really good luck in powder, that paint doesn't seem to handle, is brake fluid.... I wouldn't wash my powder coated parts with brake fluid, but it seems to handle the exposure/contact really well.

I also use WD40 to wipe down machines I work on, that are powder coated (day job). It helps keep 'em looking good, but they're also abused to the nth power. Usually the machines have been exposed to numerous corrosive chemicals and tons of temp changes and the powder only lasts so long before showing wear.... Having WD40 in the coating area is one major NO-NO.... most lubricnt sprays should be kept well out of the powder coating area.... they'll spoil a bunch of hard work really fast. No Penetrating oil sprays or the like either..... Bad news.

Alkalines and Acids all over the thing will dull the finish for sure.... So Use that as a guide for your "Ospho" contemplation. I don't think any of us coaters know what ALL will cause damage to a powder coated finish, but all of us know SOME things that will kill it pretty quickly.... I usually tell folks to treat it as good as a wet paint finish....

An Aside,....You can wax, and polish and buff powder like paint,... just be careful not to get it too hot (same as paint) or you will burn the finish,... use a low speed buffer and don't get heavy handed. A lot of guys actually color sand certain projects they shoot powder on, and use 3M Perfect-It, to get a GLASS finish.

Hope that helps.... If you have no clue to the pH of the product, do the "inconspicuous location test before using it on an entire part or in some very visible area.

Ospho is a brand name for a dilute phosphoric acid solution. It reacts with the iron oxide (rust), forming a hard black stable compound. I've used it often over the years, but I have never tried it prior to powdercoating. It tends to leave a bit of a rough finish, which I would not think would be very good of powdercoating. Unless you blasted, ospho-ed, then sanded, then powdercoated. Sounds like 2 additional steps.

volkaholic1 wrote:Ospho is a brand name for a dilute phosphoric acid solution. It reacts with the iron oxide (rust), forming a hard black stable compound. I've used it often over the years, but I have never tried it prior to powdercoating. It tends to leave a bit of a rough finish, which I would not think would be very good of powdercoating. Unless you blasted, ospho-ed, then sanded, then powdercoated. Sounds like 2 additional steps.

It does, indeed, sound like 2 additional steps. There can be parts that are not great candidates for powder coating, although it should be few. Something that you can't get powder attraction on is not going to get the durability or corrosion resistance in areas not coated fully. The good thing about it, though, is almost any are can get powder to it on most parts. Insides of pipes and tubing "can" be done as well. Once it's closed up, there's no chance though. So maybe the Ospho stuff is a good idea before outside prep of a part.

I'd like to throw another note in here, as not all parts need the same prep. It can depend highly on how the part is received. I often have to de-grease parts, even though a customer tells me they cleaned them up "real good". This adds to how much work is involved in prep, and should run the price up a little at least. Once the part is clean, and stripped of any nuisance paint or coating, I move on to Media blasting.

My goal in media blasting is to get completely to "white metal" no paint, no rust, no other plating or coating, before final prep, and shooting the powder. I know other that shoot powder over chrome no matter the color or opaqueness... but I only shoot over chrome if I am shooting a candy color and want the added "POP" to the finish (similar to the wheel in my avatar). Knowing all the time there can be no guarantee that the powder will stick like a properly prepped part. This decision is left up to the customer, as they also get no warranty from me on chipping and such.

There are more than a couple of threads on some of the PC forums that discuss the chemical resistance of powders, by the chemistry make-up the powders. There are several types of powder, just like there are several types of paints. Powder chemistries include, Epoxy, Polyurethane, Polyester, Acrylic and Hybrid powders (made up of two or more of the others).... Acrylic is probably the hardest, Epoxy the most chemical resistant.... Polyurethanes flow smoothest, and Hybrids can have "SUPER Durable" qualities, mostly to salt spray or maybe some in hardness. Polyesters are the middle of the road, but most common simply due to the typical application of the finished parts. They generally have great UV exposure and salt spray durability ratings.

In essence, you may find some powders have extremely good chemical resistance to the Ospho or similar chemicals, while others can't begin to handle it.

I know I stepped away from the last posted question, but hey,... this stuff is all good info too. We haven't even begun to step off into special effect powders either. Chrome powders, Wrinkles, veins, Candies, Metallics,.... Hell, I have one powder that looks like the part is in a puddle of Antifreeze once it's cured. This stuff is awesome.

Wow, Scott, thanks again so much for sharing...

Now, a coupe of other questions pop up:

How well would powder stand up to heat, as in brake calipers?
I have seen brake calipers done before,
But,
Knowing that it goes on/melts at 400F or so (right?)
And sometimes you see those pictures of road race cars with glowing red rotors...
Have you ever seen the powder melt off of calipers subject to severe use?
What are the chances it would survive a track day at Laguna Seca?

-Also-
The fan shroud on a type 4 is some kind of Magnesium, maybe pot metal mix.
It's straight from hell, as far as i can tell.
If it's polished, it flashes over quickly in damp weather.
(But does really nice for years in Arizona)
If polished, then tanked, then put in the oven to off-gas, paint will lift off of it a month or two later.
When i talked to my local coater, he said he wouldn't do mag ever.
I tried to talk him into doing it in wrinkle vein.
He still says no.
Think it would be worth a shot to find someone to coat it in wrinkle?
Any other ideas?

-And-
What melts, in your experience, in the oven?
I was going to do some trailing arms with the bonded rubber bushes still installed.
(Don't care for those urethane squeakers)
Also, because the rebuild kit for my Brembo 4-pots runs $700,
and they are in good shape,
And they are designed to take some high heat,
Was going to have them thrown in too...

What stuff melts, and what doesn't?


Man, it's great to get some answers...
All i get from my local guy are either grunts or frowns or both.
Always seems to include shakng of the head side-to-side, as in "No".

Just to clear up, I'll edit to get just the question, and try and cover all bases.... It's still gonna be lengthy.

Clatter wrote:How well would powder stand up to heat, as in brake calipers?

For a typical street use vehicle, powder is Awesome. Normal Powder can handle the types of temps that would be Daily driver temps.

Clatter wrote:Have you ever seen the powder melt off of calipers subject to severe use?

I have not seen powder "Melt" ever after cure. Powder coating can be had in forms that will do that, but they're not what is typically used for consumer finishes. The typical stuf is "Thermosetting" powder. If you look really hard, you can find Thermoplastic powders too,... the latter will indeed melt again at their melt temp.... but The Typical (thermosetting) powders can withstand more than their cure temp for short periods without damage. constant rises above that can be damaging. Generally speaking, powder will burn off,... not melt.

Clatter wrote:What are the chances it would survive a track day at Laguna Seca?

Simple answer,... Not gonna make it. This is where Ceramics is a GREAT idea, and fairly simple to apply and cure. It's a wet process, so I don't work with it. There are Air Cure and Oven Cured ceramics. Both kinds actually cure even more on the vehicle usually after installation of the part, and some use.

There is a new process by TechLine that is called Diamondyze or something similar, that is virtually bulletproof.... It will eat a file instead of the file eating it, at high speed, check out their website for more.... (I don't work for any of these MFgs, so keep that in mind,.. they don't pay me for nuthin')

Clatter wrote:<edited> "About my Type 4 Shroud"
Think it would be worth a shot to find someone to coat it in wrinkle?
Any other ideas?

I love shooting wrinkle powders. Funny thing is, they're actually quite easy to keep clean too.... contrary to popular belief.

If it's metal (and especially if it's not a critical running or structural part) It can be coated. What I find interesting is there's a coater afraid to coat Magnesium..... weird.
There should be a coater that will do your shroud for you in just about any color or finish (Including a blasted or polished "look" finish) that will hold up for many years. Find another coater would be my best advice.
The biggest issue that anyone can be up against doing anything like your shroud, will be getting past the outgassing ruining a perfect finish.... there are a few ways around that, that are simple, and your coater needs to figure them out so he can take in more business (That is... if he WANTS to make money at coating). There are Primers that will eliminate ANY outgassing. And there are prep steps to help reduce them,... using every method available on the same piece pretty much Guarantees no issues. The type 4 shroud is cool looking and would look great coated to match your vehicle or maybe even a contrasting color. Again.... maybe a different coater is what's in order. I've seen Magnesium clear coated with powder.... a bunch. but I'd probably recommend a color instead.... There are so many colors and textures available, you'd fall over if you could see them all. One of my suppliers actually touts "Over 6500 colors"....

Clatter wrote:What melts, in your experience, in the oven?

This had to come up eventually.... so it's pretty much Metals are good,... plastics and rubbers... not. I also coat Glass at times, since most glass is good for the temps.... just gotta clean to prep (Blasting if you just know what you're doing). I usually shoot candy colors over clear glass for decorative purposes... so I want it clear. Want candy colored glass on your bug? Can Do!
Although there are some composite plastics that I do indeed coat. I do a lot of research to figure out if it will take the heat or not before starting any prep. If I cannot verify the temps, I don't coat it. Some plastics deform or melt at temps close to recommended cure temps, but can still be coated if you cure for a lower temp and longer time.... this is a delicate balancing act, and shouldn't be something that just anyone tries on their neighbors $1700 intake.... Example: FAST 3 piece LS intakes, will handle well over 400 degrees before any bad things happen.... The factory ones just barely over 400.... The composite plastic is much thinner on the FAST intakes, but they're designed to handle the heat more. *wonder why*
Rubber IS degraded when exposed to the temps for curing powder... a lot of them will make it through, but have lost some of their service life... A very large part of their sevice life.
Things like solder and pot metal can also be a problem as some pot metals melt at low temps, and of course the content of the lead in the solder will decide on it's melting temp. Aside from those two, I don't know of any metals that can't be coated.

Clatter wrote:Also, because the rebuild kit for my Brembo 4-pots runs $700

I just left that last part in to say "OUCH! That's pricey for a rebuild kit. Doesn't sound fair at all for parts. And I wanted to address this particular item as a subset. I know Brembo is a big name known for Big Brakes.... doesn't someone else build some decent brakes that don't cost an arm and a leg? Sheeeesh. They're just brakes.....
In my knowledge base, Brembos generally are assembled using large O-rings. If you can disassemble them carefully not damaging the seals,... you should. They're super simple assembly is one of the things I like about good performance brake calipers.
I really do recommend a new kit when coating calipers, and coat them completely raw. They have to be washed out completely and prepped as anything else, masking off all relevant surfaces.... the bores, bleeders, inlets....

Clatter wrote:Man, it's great to get some answers...
All i get from my local guy are either grunts or frowns or both.
Always seems to include shakng of the head side-to-side, as in "No".

I do that too....(nod and grumble), but I really will go out of my way to help a guy out. Customer or not. I generally help out at least one or two new coaters in my area every year. last year was really heavy and I helped out about 5 of them. I let them come try the stripper I use, check out my "homemade coating booth" my ovens, and try out my guns before they spend money on this stuff.... Like I said somewhere earlier.... I've got well over $10k in my coating operation, in equipment alone. And I just added a new Blasting pot, and a welding rig.... (that part may be useless too, but I'm diggin' learnin' to weld). It's a very addictive "hobby" and a fun business to be in. Creativity being the limits to what can be done (Well,... as I mentioned in another thread, the pocket book can limit also)

To expand on folks understanding of what's available,..... here's a few color rings from one of the suppliers I use..... This isn't even close to all of their colors available. There's solids in the middle, on the right River/hammerton/vein and Cast effect.... the left side is a grouping of Candies and Transparent powders, the top ring is Two coat powder colors, a lot of them are a metallic over a black base or chrome base, and a few of them are what's known as Illusion or Dormant powders that don't show their true color until you apply the clear coat or top coat.

Can you paint my house? I mean powdercoat it...........what some color choices.

david58 wrote:Can you paint my house? I mean powdercoat it...........what some color choices.

As long as your house can take the cure temps.... WE could do it. You would have to be involved on a grand scale...

Like said previously.... the powders are as many as wet paints.... special effects and all.

I have been powder coating or @ 6 years. I am hoping to be able to do this when I retire one of these days. I am glad somebody else is powder coating there vw parts. We (the wife and I) have a 69 karmann ghia race car that we powder coated the whole car before we started building. For the home hobbiest, there are a few different ways to go. You can get the el cheapo's but that is were the quality is also. There are some medium priced (under $2k) guns that do a jam up job for the piece mill work. of course if you are running a major business and this is what you do 24-7-365 then its north of $10k. I powder coat everything i put on my car. The gentleman said it with his tips on how to get great results but what I think is the most important one is the pre-heat "outgassing" especially with old parts.

r1cpowdercoating wrote:I have been powder coating or @ 6 years. I am hoping to be able to do this when I retire one of these days. I am glad somebody else is powder coating there vw parts. We (the wife and I) have a 69 karmann ghia race car that we powder coated the whole car before we started building. For the home hobbiest, there are a few different ways to go. You can get the el cheapo's but that is were the quality is also. There are some medium priced (under $2k) guns that do a jam up job for the piece mill work. of course if you are running a major business and this is what you do 24-7-365 then its north of $10k. I powder coat everything i put on my car. The gentleman said it with his tips on how to get great results but what I think is the most important one is the pre-heat "outgassing" especially with old parts.

Glad to know there's another coater on board. This is actually one of those processes that's a "made for" VW's, kind of thing. And even more so when considering restoration of any old car parts in general. Nothing beats Powder unless you're coating exhaust sections.... then maybe it's time to delve off into some ceramics or Thermal Dispersing coatings.