I did a foolish thing - Epoxy primer and rust converter

[qz16]

I did a foolish thing!

 

Background:

Most of the car has been taken to bare metal.  The rear clip is painted.  So, I am in the process of doing the final prep work to paint the remainder – fenders, doors, hatch, hood, etc.  I was trying to finish some of the remaining pieces, but you know how it goes.  Every time I passed a door I saw something else, a tinge of rust color I thought, a place that would benefit from a little bit of filler.  I just would not let it go.  One of my favorite saying is that the enemy of good is better.  Unfortunately, I can remember it but I am still unable to practice the sentiment.

My total experience spraying is limited to 1.5 cars, an MGB which came out fairly nice and the z which is turning out even better.  I have no experience with Epoxy primers, or Etching primers.

Fast forward  based on what I have read I decided that I did not see the benefit of applying an etching primer.  On the other hand, the corrosion resistance and the concrete separation between anything below it and what would be laid on top of it was attractive to me.

So, my plan for the remainder of the car was to continue doing most of my body filler work on bare metal, and to apply an epoxy primer.  This would be followed by a Urethane (high build) primer, base coat and clear.  Of course, there would be the appropriate amount of block sanding between spray layers. 

Now I promise to TRY not to be sensitive.  I really do want to learn, so don’t hold back if I say something less than brilliant please do not hesitate to point it out.

My understanding is that Rust is bad.  It should be completely eliminated before any primer/paint goes on the car.  That’s why we took most of the bucket to bare metal.  Having said that there are places that you just can’t get to, or just don’t want to because the risk vs. reward is just not balanced in your favor.  So, there are places where I have (dare, I say it) sprayed rust reformer or converter.  I’ll give you an example – the front of the door was taken completely down to bare metal.  The back of the door - not so much.  It was sanded, and when I got to the edge of the door skin that wraps around to the back I wire wheeled them.  This revealed some pitting and some superficial rust.  On the door skin I removed the rust with Eastwood rust dissolver, a very good product in my opinion.  But on the rust on the frame of the door I used rust converter.  Now I know you are thinking that this was a rookie error.  However, if I were going to do the perfect job then I would need to remove the skin from the door to make sure that there was no rust behind the skin, but I know that this task is beyond my skill level, sure I could get the skin off but could I get it back on the door in as good a shape as it is now?  So, using rust converter was small potatoes given that I was not going to remove the skin.  Also, to be honest, the car is 45 years old it was obviously mistreated at one point in its life and the rust that I am seeing is fairly superficial so I think it is a reasonable bet that these doors will last a long time given the level of care that I am applying to the car.

I apologize if this is boring you, but here comes the punchline – I believe in the notion that if I can see rust then there is always some that I can’t see, and I can’t deal with anything that I can’t see.  So, I foolishly spray converter into the door frame, it will not do much good but it makes me feel better, it wont in my opinion do much harm either.  But now I have the darn can in my hand and I go one step farther.  I spray it on the entire back of the door, and since that was such a good idea, I spray it on the back of my fenders, and the back of the headlight coves (I think they are called that).  By the way before I sprayed the rust converter I roughed all of the surfaces with 80 grit.  Everything looks good.  It looks uniform. If there’s any rust I converted it – hell if the rust were English Pounds I would have converted those pounds into a million U.S. Dollars.  Now everything is drying and I start thinking.  Then I start reading.  And now I start worrying.  I am totally confused by what I have read.  I know that I should not cover rust with epoxy primer, and to my knowledge when I spray the epoxy I will not be covering any rust.  The question is can I spray epoxy primer over rust converter?

So, I decide that the damage has already been done and I need to do some experimenting.  I don’t have to spray the epoxy on the back of the fender so this will test whether I can properly spray epoxy primer on bare metal, and body filler.  My inspection doors have body filler on the top side, but nothing on the back side.  So, this will show if I can properly spray epoxy on just bare metal (the backside).  The headlight coves – I decide to spray epoxy on the top and backside.  This will give me some insight into what happens when you cover rust converter with epoxy.  In this particular case below the rust converter on the back of the cove there is rust free bare metal ( they were sand blasted), which I then sprayed rust converter on. 

Now as I have come to understand it epoxy primer sprayed over rust converter will cause the primer to lift. 

So, my foolish mistake is that I thought the rust converter would not hurt anything and it might help prevent future rust from forming.  This in my opinion (now) really was stupid.

 

Conclusion:

All of the pieces that I sprayed turned out great.  The epoxy has been on for approximately 4 days at this point, I think that is somewhat important because most epoxy primers have an open window of 72 hours..

1. The fender with the mix of filler and bare metal – sure you can see where the filler is but the epoxy went on fine as it should and the filler will certainly be covered by the high build urethane that follows. – so, no harm no foul.
2. The inspection doors same thing no issue on either side.
3. The headlight coves came out perfect.  The epoxy covered the rust converter – you would never know that there was any converter applied.

So, I called the Rustoleum company and spoke with one of their specialists.  They in no uncertain terms told me that you definitely should not cover any rust with epoxy primers.  Furthermore, you should not cover their rust converter with an epoxy primer.  I asked if that meant that I needed to sand off all the converter.  I was informed that would not be necessary.  Rustoleum makes a product (a shock) called clean metal primer.  It could be applied over the converter and either urethane primer or base color could be sprayed on top of the clean metal primer.

So, I know that you will be glad to hear that this tale is almost ended.  My question to anyone with direct experience:

a. If you rough the surface (covered with rust converter) with 80 grit can you spray Epoxy primer over it or will it lift over time?  

b. Is there anything (other than rust) that you should not spray epoxy over? 

c. The epoxy primers that I have looked at all say that you can spray them on bare metal, properly prepared paint, body filler ...etc. If epoxy primers require a mechanical bond and you rough with 80 grit why can't you apply epoxy over just about anything.

 

I purposely have not mentioned which epoxy primer I am using as I do not want to get into a discussion of which primer is better than another.  If you do like one better than another please mention it.

 

As always thanks for your patience and for sharing your knowledge.

 

 

 

[grannyknot]

10 hours ago, qz16 said:

One of my favorite saying is that the enemy of good is better. 

Ain't that the truth and where is the line between them?

Eastwood rust converter or Ospho or any of the other products are just phosphoric acid, it converts iron oxide into iron phosphate. You have to remove as much of the rust as possible before applying it because it can convert the top layer and turn it black (iron phosphate) and leave rust underneath. You apply it and must keep it wet to keep it working, if it dries you will end up with the white powder and no paint or primer will ever stick to it, you will have to sand it off.  You need to wash the converter off while it is still wet with water but even then I have still ended up with the white powder.  I don't use phosphoric acid any more because it is such a pain in the arse.

It sounds like the rust remover/dissolver you are using is the Evaporust type, not an acid, works by displacing the oxide ions with a chelating agent.   Immersing the rusty part in the rust remover works very well and you can just paint over but I do wash it before priming. Using the gel type rust remover for vertical surfaces is much more tricky, the ones I have used are not really gels as much as a blob of snot like material that does not want to spread, I haven't tried Eastwoods version yet hopefully it is better. With the gel type you need to cover the applied area with Saran wrap to keep it wet and working but you really don't want the gel type to dry. It becomes this hard crust that can be very difficult to remove.

The above is just my experience and my understanding of the chemistry,  so what should you do?  That takes us back to the lines between good, better and perfect, you will never get all the rust, every seam has some,  I remove as much as I possibly can and seal it up with 2k epoxy primer, that at least will slow it down as much as possible.

So sand off anything that looks whitieish, nothing will stick to that stuff.

Edited December 9, 2018 by grannyknot

[qz16]

granyknot - thanks for the quick response.

I am using Rustoleum Rust reformer.   I am also using eastwood rust dissolver which is water based.  it is especially useful on pitted areas.  I scrub it in with a scotchbrite, wire wheel it, apply pre prep, and dry it.  I have used eastwood fast etch, but try to stay away from it as much as possible.  As I understand it etching chemicals are stronger, but can only be applied on bare metal.  This limits their use in my garage.  Even when I have the right situations I always attempt to use the rust dissolver first.  I also use eastwood pre prep for wash down and dry with compressed air before I prime a panel.  I really like the eastwood products that I have tried.  Sometimes their stuff seems a bit pricey, but I have found it to be high quality.  The only thing that bugs me with Eastwood is that it takes forever for them to process, ship and deliver.  All of the coatings (paints/primers) that I am using are 2k.  I have used gel type strippers, but have not used any gel type rust removers or gel type etching products.  I know about the chalk like powder.  Have not seen it happen all that much.  Good advice - thank you.

 

[Patcon]

I would love to know what epoxy you're using. I don't think it will hurt the product reputation at all, since it seems to be bonding. I have used Nason epoxy on bare metal that I had treated. Now we sand everything pretty good after we treat it, and I have had no bonding issues from that. The only paint failures I've had are from active rust under the new paint. I do know that they don't want you to acid treat metal before epoxy, but I have done it successfully so far. Most of the body guys I've talked too tell me I need to paint bare metal the same day. That I can't let it sit without painting it. It's just not really feasible for me to do that sometimes. I keep the humidity in my shop pretty low so the metal doesn't really surface rust when it sits.

[qz16]

Patcon, thanks for the comment - I am not trying to be coy its just that sometimes on forums the topic at hand morphs into commentary on who likes what manufacturer.  Anyway, I did not know what to buy and decided to go with a brand that I have used before.  My base and clear coat are PPG deltron, very pricey stuff - not sure if it is worth it or not.  For the epoxy primer I went with PPG OMNI MP 17x series.  I have read and seen a number of complaints and stories about difficult to spray, gummy, etc.  I have nothing but good things to say about the product but that is not based on a ton of experience.  It sprayed great, It looks fabulous - but it is primer.  No orange peel, no problems with gassing off too slow or too fast.  It appears to be somewhat self leveling.  I put two coats on.  My primer gun is an air gunsa AZ3 with 1.8 HTE tip.  Sometimes people blame the product when it is a skill issue, or equipment issue, or setup issue.  I'm at the  point that its just easier to blame me.  I have heard good things about Nason products.

Based on your comment that you sand everything I assume you are using an etching product or a water based product like rust dissolver.  I think you are correct as long as you wash down the panel and dry them thoroughly the chemicals work great.  I have come to the conclusion that the only time to use rust converter type products is for place you just cant get to very easily, like the bowel of a rocker panel, or into the fold of a fender.  And in these types of situations it is more of a wing and a prayer for areas that you cant see the rust.  This morning I tore into a fender that I had used rust converter on a year ago.  I did this because I saw a pinhole in what was good metal a year ago.  I kept hacking away trying to get to clean metal and what I found was that the converter had worked on one piece but a second piece that was sandwiched to it showed no sign of reform.  The rust was fresh and active.  So today I am less of a fan of rust reformer/converter than I was 48 hours ago. 

I  am just a DIY guy and so it is a bit of a production to switch from mechanical work to bodywork to paint, so like you I am not able to put paint on the same day that something gets stripped, unless I was going to rattle can it.  I am not sure what is best  - to use the etch and let it dry to protect the piece until you can get to it or to deal with the rust if you are unlucky and it does form.   I have very little control over the climate in my garage, so I will not spray below about 55 deg. and never even tried above 40% humidity.  I am lucky though I live in phoenix so temperature and humidity favor me most of the year.  Biggest problem I have is very quick drying when the temps are high.  

Turns out that most of the time when I do something foolish I just need to lick my wounds,  the right answer to my mistakes rarely turns out to be an easy or quick solution.  But I will not make this one again.

Once again, thanks for the response. 

regards,

ron

[Patcon]

48 minutes ago, qz16 said:

Patcon, thanks for the comment - I am not trying to be coy its just that sometimes on forums the topic at hand morphs into commentary on who likes what manufacturer.  Anyway, I did not know what to buy and decided to go with a brand that I have used before.  My base and clear coat are PPG deltron, very pricey stuff - not sure if it is worth it or not.  For the epoxy primer I went with PPG OMNI MP 17x series.  I have read and seen a number of complaints and stories about difficult to spray, gummy, etc.  I have nothing but good things to say about the product but that is not based on a ton of experience.  It sprayed great, It looks fabulous - but it is primer.  No orange peel, no problems with gassing off too slow or too fast.  It appears to be somewhat self leveling.  I put two coats on.  My primer gun is an air gunsa AZ3 with 1.8 HTE tip.  Sometimes people blame the product when it is a skill issue, or equipment issue, or setup issue.  I'm at the  point that its just easier to blame me.  I have heard good things about Nason products.

Based on your comment that you sand everything I assume you are using an etching product or a water based product like rust dissolver.  I think you are correct as long as you wash down the panel and dry them thoroughly the chemicals work great.  I have come to the conclusion that the only time to use rust converter type products is for place you just cant get to very easily, like the bowel of a rocker panel, or into the fold of a fender.  And in these types of situations it is more of a wing and a prayer for areas that you cant see the rust.  This morning I tore into a fender that I had used rust converter on a year ago.  I did this because I saw a pinhole in what was good metal a year ago.  I kept hacking away trying to get to clean metal and what I found was that the converter had worked on one piece but a second piece that was sandwiched to it showed no sign of reform.  The rust was fresh and active.  So today I am less of a fan of rust reformer/converter than I was 48 hours ago. 

I  am just a DIY guy and so it is a bit of a production to switch from mechanical work to bodywork to paint, so like you I am not able to put paint on the same day that something gets stripped, unless I was going to rattle can it.  I am not sure what is best  - to use the etch and let it dry to protect the piece until you can get to it or to deal with the rust if you are unlucky and it does form.   I have very little control over the climate in my garage, so I will not spray below about 55 deg. and never even tried above 40% humidity.  I am lucky though I live in phoenix so temperature and humidity favor me most of the year.  Biggest problem I have is very quick drying when the temps are high.  

Turns out that most of the time when I do something foolish I just need to lick my wounds,  the right answer to my mistakes rarely turns out to be an easy or quick solution.  But I will not make this one again.

Once again, thanks for the response. 

regards,

ron

I totally understand all of this from my own experience

I have used the Omni epoxy in the past. The only issue I had was, epoxy shouldn't come off with lacquer thinner after it's cured. I was able to wipe some Omni off many years ago. Now I don't know if that is my fault or a product issue. One of the issues I always have with my paint is the catalyst get bad over time and I use them slowly by industry standards. So it may take me 2 years to use a full gallon of epoxy or primer or what ever. So it may be the catalyst I used in the problem Omni was bad and just didn't cross link. I use Nason products now which are basically the PPG products of say ten years ago. PPG develops a new better product then repackages the current PPG into a product for the Nason line. A body shop guy told me that just last week. PPG makes good product, albeit not cheap. If you DIY though you have a lot more room to by materials because you save so much on the overall cost of a paint job.

I have had good luck with Eastwood products. Although I have 2 complaints about them. One is an Echo. In these days of Amazon Prime, I would like to see my product arrive faster than it does. The second is that their product is fairly expensive. I have been using their "After blast" for bare metal protection. It is an acid based product that converts light rust to phosphate and protects the panel from flash rust. For concealed areas I have used the "Internal frame coating" I buy the cans with the long hoses on them and I filled every concealed space on the z before I got very far along into body work. It is runny and will seep out of all the seams and drip everywhere. Don't buy the bulk can because you will never be able to get it to spray out of anything. It just dries way too fast to spray it out of an undercoater gun. Also the cans of internal frame coater don't store well. Buy them when you need them and use them. I had 2 cans that sat for a while and were dead when I tried to use them. They are too expensive to have them be dead from sitting.

I do like their 2k satin black for matching the Datsun chassis black and black out areas. I made my own sating black for a while by using a flattening agent but I get more consistent results in finish using the Eastwood product. I try to use Evercoat products for fillers, and I am using sort of middle of the road Devilbiss guns. I have multiple tips so I can match the product.

Have you ever looked at the P sheets for the products you use? I have a 1" 3 ring binder I keep in the shop with copies of all the P-sheets for the products I use. That way I don't have to remember mix ratios or recommended grit levels for each product. They will have little details that make using them easier.

I however live in the deep south and I run a dehumidifier 24/7 in my shop to keep humidity at bay. If I don't run it, stuff rusts up pretty quick and mold starts growing on everything.

Sorry for the novel...