Metal Prep for Epoxy

[Gav 616]

Hoping to get some advice here. I've abrasively blasted the floorpan of my XA and wish to prepare it further for an epoxy substrate. I'm planning on using Protec Epoxy AP-4110. The literature for this material suggests the use of a phosphoric acid cleaner/metal conditioner. I was planning on prepsoling the floor then using the metal conditioner as suggested. I did a test patch using the metal conditioner. this is what I got :

 

 

or more diluted :

 

 

Is this the effect I'm after? Looks suspiciously like corrosion...ie. iron oxide. I assume phosphoric acid reacts with the iron component of steel to produce iron phosphate...which in the case of a metal conditioner should be a useful ultra thin layer. Googling "iron phosphate" produces images of a material that's a similar colour to iron oxide (rust) - so perhaps this is the effect I'm after.

 

I've  used metal conditioner before on much smoother metal and it produces a blueing effect. The floorpan is more keyed because of the use of 30-60 grit to abrade it....is the different result because it's not as easy to remove the conditioner from the micro pits created by the sand blasting?

 

Am I on the correct track? I don't want to apply this stuff to a huge floorpan and engine bay area only to find I've screwed things up royally. It seems a shame in a way to convert my yummy bare metal floorpan to this orange stuff. Ando76...if you're around, what do you say?

[revhead 1,392]

when I used epoxy on bare surfaces ,ppg told use to clean the area with metho and scotch brite ,at to remove any oil, as prepsol is an oil based cleaner ,with the epoxy for spaying we did thin it a little more and also ran it through paint strainers as it contains the odd lumpy bit of shit ,and the most coats used or recommend was 2,only

 

also don't forge to put a light dusting of etch primer first to give the epoxy something to grip to,

[xm-221 1,803]

also don't forget to put a light dusting of etch primer first to give the epoxy something to grip to,

Protec Epoxies generally don't need an etch coat. They work best over bare steel.

 

Gav, does the literature you've got say it's for sanded surfaces or abraded?

Whilst she's on her side blow all the dust from the blasting grit off, wiping with a rag as you go. Then get a pump pack that you can put thinners in and give her a wash from top to bottom, again wiping as you go. You'll go through a lot of rags but she'll be clean enough for the epoxy after that.

[ando76 4,354]

I always use PROTEC metal conditioner on freshly bared surfaces - whether they are hand/chemically bare metalled or blasted.

 

PROTEC metal conditioner is phosphoric acid and yes it will leave a coppery/rust like coating when prepared properly or bare steel.  I only use EPOTEC on bare steel.  It is a 2pac - primer filler and etch all in one.  We have to do it this way in the tropics because of the humidity.  Bog on bare up here and you are in big trouble.  same for any single pack left for a short period.

 

I highly recommend EPOTEC over bare.  I can show numerous examples of cars that have been done this way and are still rust free - have no humidity blister or rust creep.  And that is cars that live here in Cairns we have rusts best friends, humidity, rain and salty air.

 

If you are using PROTEC metal conditioner and then going over that with a 2K primer (EPOTEC) then follow the instructions on the bottle.  It will scare the shit out of you but you wash it off with water (yes water) and then blow it off so it is thoroughly dry (yes it will go that coppery colour) and then hit it with your EPOTEC. 

 

YES you WILL shit yourself and think this is wrong it's all rusty like - I'm doing this wrong.  Trust me your not.  Way back when I showed you those photos of the door where I had run the punch and flange too in and repaired the lower section - well that door was treated that way.  It is still sitting in the exact same position as when I took that photo and has been there for 3 years and shows no signs of rust creep or nothing.  And it has been hit with the hose numerous times as I hose down the floor before painting and it cops it. 

 

So short answer is - follow the instructions on the PROTEC metal conditioner for 2pac priming and you will not go wrong. 

[Gav 616]

Thanks for your responses. It's very comforting to know I'm heading vaguely in the correct direction. It's not every day you turn your car upside down and paint its bum. 

[blu xe 825]

Ando76 is spot on. Metal conditioners when used PROPERLY are awesome. If not done properly though can lead to bigger issues later down the track than if you hadn't used em in the first place. We use a ppg metal conditioner and yes it must be cleaned off with water and nothing but water. This is what neutralises the acids . I totally soak a rag then wipe the bulk off then come back over with 3 more times with damp rags to get the rest off. Then dry with a air. Something else to consider is not letting it get in between seams and joins because it will be hard to guarantee that you have in fact nuetralised it. Which will be hard to do on the underside of the car.

To be honest if you've blasted it clean I'd be inclined to just clean up the grit and ep straight over what you've done. With any bare metal prep I do I ALWAYS will only strip as much as I know I can prime straight away. So for panels i'll do say 2 doors at a time. Starting on 1 panel includes paint removal orby finish back to bare once the bulk is gone then metal conditioning then another pass with the orby with 80 or even 40 grit to really key it up then epoxy it immediately. Then move onto the next panel. Up here we have to be very particular with the whole process because of the humidity. It may sound like paranoia but this is what works for me and I've done more than a few bare metal jobs that are 7 plus years old now that aren't showing any signs of funky shit playing up under the paint.

[ando76 4,354]

Exactly blu xe - how many southern cars have you seen come up here and after 3 months the paint is full of humidity blister and falling off???

 

Old Greg and I will make our retirement very comfortable thanks to those cars.  Lol. 

[blu xe 825]

Yes seen many pretty cars turn to shit once they make the move to FNQ. A half assed job doesn't stand a chance in our conditions. This is always something that shits me when someone comes in and freaks out when we give them a rough idea of what they will be paying to have a job that's covered by a lifetime paint warranty and done to a standard that we think needs to be adhered to , to have half a chance of surviving up here.. Its always the case of so and so down the road will do it for half of that then complain about it when it goes to shit cause they were to tight to pony up the proper dollars to get the job done right! A lot of these same people are happy to sink 20g plus into an engine that will go bang the first time its leaned on and are perfectly ok with that cause its a race motor that shit happens! But fark its on like donkey kong if their cheapy $5000 paint job blisters up after 6 months .Go figure!LOL.

Rant over back to topic now!

[PRO250 1,506]

Im playing with a car atm thats been blasted and i just scuffed it up real hard, I cleaned it and shot the epoxy over it i did treat a few spots that looked a little iffy but im much happyer shooting over somthing thats clean and shiny than over a metal prep. Its working for me so far so i hope im doing it right 

[Gav 616]

I finished blasting the pan on Friday...still looks okay...but I know corrosion is already taking place on a microscopic scale. Actually..it's macroscopic cos when you scuff the metal...you can see that freshly exposed metal is a little brighter than the surrounding metal the corrosion process has already begun.

 

My thinking on this lurches all over the place. This morning, after Ando76's input, my thinking was that I was all set to resume the phosphoric acid metal prep, post prepsol. Now I'm beginning to believe it may cause more issues than it solves because there are a lot of seams and double panelled areas that will capture metal prep, water and other crud. There's a greater probabilty that this will cause issues rather that the microscopic flash rusting that occurs over two cold Melbourne days on a vehicle that is a dry, well sealed shed.

 

Gonna go and have a poke at the car tonight. Hopefully the answers will come to me. The big day for painting is supposed to be tomorrow. One of the kids looks like she's getting "pink-eye". Can you believe it? Bare assed car, semi-confusion about what to do, a day off work tomorrow, a kid child-care will send home quicker than....feck knows what....I am living the dream!

[blu xe 825]

Other option is re blast it in smaller sections and epoxy it in more managable sections if your worried about it.

[Gav 616]

Other option is re blast it in smaller sections and epoxy it in more managable sections if your worried about it.

 

I think you may be correct here. I'm normally quite cautious by nature when it comes to things like this. I typically like to sit back and consider things...as the answer to any problem usually arrives quite naturally after some quiet research and consideration. Funny really. What's caused this rush in a way. Last week, one of my compressors that I use to drive the sandblaster packed up. The remaining two, by themselves are insufficient to drive the blaster really effectively. So I hired, at considerable expense one of those trailer mounted (130cfm) suckers from Kennards. Suffice to say with that much air (and money on a per-day basis!) I tore through the paint on the underbody without a lot of consideration as to what was to follow. I have also scheduled this project and have set deadlines that appear a litle unrealistic. So time to settle back and relax.

 

What I think will do is mask of the underbody with builders film in an effort to limit atmospheric damage. I can expose smaller areas at a time and keep other areas sealed off. that way on re-blast, I can limit the amount of re-cleaning etc that needs to be done cos sand and other shit get everywhere when blasting. I'm feeling more content already! A solution of sorts. Now I can sleep a little better tonight.

[blu xe 825]

Yeah mate might be the safest option and ease your mind. It is easy to get ahead of yourself doing this sort of stuff. Sometimes over enthusiasm can bite you on the ass! Rome wasn't built in a day hey. Lol

[Gav 616]

I always use PROTEC metal conditioner on freshly bared surfaces - whether they are hand/chemically bare metalled or blasted.

 

PROTEC metal conditioner is phosphoric acid and yes it will leave a coppery/rust like coating when prepared properly or bare steel.  I only use EPOTEC on bare steel.  It is a 2pac - primer filler and etch all in one.  We have to do it this way in the tropics because of the humidity.  Bog on bare up here and you are in big trouble.  same for any single pack left for a short period.

 

I highly recommend EPOTEC over bare.  I can show numerous examples of cars that have been done this way and are still rust free - have no humidity blister or rust creep.  And that is cars that live here in Cairns we have rusts best friends, humidity, rain and salty air.

 

If you are using PROTEC metal conditioner and then going over that with a 2K primer (EPOTEC) then follow the instructions on the bottle.  It will scare the shit out of you but you wash it off with water (yes water) and then blow it off so it is thoroughly dry (yes it will go that coppery colour) and then hit it with your EPOTEC. 

 

YES you WILL shit yourself and think this is wrong it's all rusty like - I'm doing this wrong.  Trust me your not.  Way back when I showed you those photos of the door where I had run the punch and flange too in and repaired the lower section - well that door was treated that way.  It is still sitting in the exact same position as when I took that photo and has been there for 3 years and shows no signs of rust creep or nothing.  And it has been hit with the hose numerous times as I hose down the floor before painting and it cops it. 

 

So short answer is - follow the instructions on the PROTEC metal conditioner for 2pac priming and you will not go wrong. 

 

Just re-reading the posts in this thread.....and something came to mind that may be of use to folk here. Anyone noticed that PROTEC have considerably rationalized their product line-up? Seems PPG (Protec's owners) are pulling Protec's expansive, duplicating product offerings into line. My local Protec rep has said as much.

 

Anyway, they offer two epoxies. EPOTEC 408 is apparently their industrial coating and AP-4110 is more oriented to the automotive sector. Reading their product literature...each has slightly different prep and curing behaviour. The EPOTEC is supposed to be applied to bare, freshly blasted metal -  within 15 minutes apparently - although I don't see how this can be practical in a lot of cases. With the AP-4110 it is suggested to apply it over a metal prepped surface. I suppose though...it to could be applied over a freshly blasted surface too.

 

Has anyone noticed when it comes to certain issues....such as underbody prep...there are so many opinions? Trawl the internet and you'll find so much conjecture...as much informations as misinformation. It's often difficult to arrive at a firm conclusion on a lot of issues.

 

Thanks for your input chaps. And...geez...everyone says the southern states have got the shitty end of the stick as far as weather is concerned...we got it good in comparison to the Queenslanders who've helped out here it seems. I reckon it's far easier to control for "cold" (thanks "Jetfire"!) than it it to control for "humidity".

[ando76 4,354]

No worries mate.  And yes the internet can confuse issues at times, but really when you have two people from the same crappy weather region, where rust is a major issue, telling you the exact same thing - well there has to be something in that.  If we were both wrong we would have a lot more 'comebacks'. 

 

Greg - my mentor - has been using EPOTEC, the old green/grey, for more years than I can remember and he never has comebacks. He loves the stuff that much I reckon he has a spoon full for breakfast.  When we heard PPG were taking over PROTEC we both bought up a good supply of the old PROTEC EPOTEC so I have not had to deal with the changeover as yet.  That will be changing shortly as I am on my last EPOTEC kit.  bugger.

[Simon Wright 0]

Sorry to revive this thread , but for those that have used epotec 408...... i spray a few pots of it on a shell the other day and got 3 results....some sections came up a dull powdery finish and hardened up nicely. another very shiny smooth but hardened up nicely, and the third which after a week is still tacky....

possibly explanations??

 

thnaks in advance, obviously i haven't done this before and believe i have mixed correctly. 4:1

[blu xe 825]

What was the temperature like while you were spraying? Have to have the panel warm before you spray or it can stay tacky and may not even fully cure cause the top has skinned off before the first coat that's  directly on the substrate has had a chance to cure. You'll know cause as soon as you try to sand it , it'll ball up and start pulling away from the metal. If you can pull up an edge with your nail your going to have to strip it and start again. Also need to give it enough time to flash off between coats. I generally do my first coat then wait till it looks eggshell like. Then once you can lightly stick a finger on it with out it actually being wet go the next coat. If you go a third coat then the wait time is even longer.