Epoxy Primer vs Self Etch Primer for Bare Metal

Epoxy Primer vs Self Etch Primer for Bare Metal


-Hey, this is Donnie Smith. In this video,
we’re going to talk about mixing epoxy
primer because we’re going to mix up
some epoxy primer and put it on the project
we’ve been working on. Now first, I want to talk about
epoxy primer just for a minute because there’s a lot of
confusion, a lot of questions I get asked about primers. Now, epoxy primer is for metal. It’s for corrosion
protection, and it also helps with adhesion. But it’s not the
only primer that you can use for bare metal. It’s just one option,
and some people ask if they have to use both of
them like that and self-etch, and it’s an either/or. So both epoxy primer
or self-etch primer, self-etching primer, can
be used on bare metal. Both provide
corrosion protection, and both can be top-coated
with primer surfacer. For example, if we’re doing
body work in this area, and we have some
metal, well, you don’t want to put just
regular primer surfacer, 2K primer on top that, because
it does not have the corrosion properties like
epoxy or self-etch. So how do you choose if
you use self-etch or epoxy? Well, really, that’s
just a preference, whatever you prefer. And here’s what
I think about it. If you’re a restoration
shop, you’re probably using more epoxy. If you’re a high
production shop, you know, like a body shop that
runs a lot of cars through, you’re probably using self-etch. Now here’s the
reasoning behind that. Epoxy is the only
primer that you can put body filler on top of. You shouldn’t apply body filler
on top of self-etch primer or primer surfacer,
but epoxy it can be. And myself, if I had a car, and
I had it blasted or stripped to metal, that would be the
best thing, in my opinion, is to put epoxy
primer on top of that, especially if you’re going
to be doing some body work. That way, you seal it
all off and prevent it from rusting any, and then
you can do your body work. Now if I’ve got just a
small area of metal here, you know, I may
not mix up epoxy. Self-etch may be just fine. And there are some 2K self-etch
primers that are used too. Even if this complete
panel is bare metal, they can go ahead
and that on there. So it’s just kind
of a preference. In this video, I’m using epoxy,
but I could have used self-etch as well on the bare metal. Some advantages of
epoxy over self-etch is epoxy is very friendly,
user friendly, is very compatible
with other products. You don’t have to worry
about anything lifting like you might with
self-etch primer. So epoxy, you can lay it over
just about anything, the body work, sanded paint, metal,
and you’re going to be fine. Self-etch, if put that over
the different layers of paint and everything, sometimes
if you put that on too wet, it’s going to lift because
self-etching primer has acid in it. So you need to be aware of that. Some advantages of self-etching
primer over a epoxy is it’s a little bit simpler. There’s no induction times with
self-etching fetching primer. And there is even a 1K
product that works well for corrosion protection, and
it even comes in a spray can. So if you have just
a small area you’re wanting to apply such
corrosion protection to, that self-etching primer in a
spray can may be the way to go. Very simple. What is my preference? Well, this is what I like to do. This is not the only way. There are a lot of
ways to do this. If it’s a bigger area, let’s
say bigger than a silver dollar size, I’m going to go ahead and
mix up some epoxy and use that. If it’s smaller
than that, I’m just going to get the spray
can of self-etch primer and hit it with that. You know, before I seal
or apply primer surfacer. But rather than get too
concerned about which one you should use, I mean,
they will both work fine. Thing to remember is
if you have bare steel, don’t just the primer
surfacer on it. Put one of those two. There is one third
option, and that’s DTM, Direct-to-Metal primer. And what that is, it’s
a primer surfacer, so you get your
sandability with it. But it also has some
acid in it, which acts like a self-etching primer. DTM can be applied
directly to steel and then sanded just
like a primer surface. But in this video,
we’re going to show you how to mix up some epoxy
primer, and then we’re going to apply it to the
project we’re working on. Once the epoxy is
applied, then we’re going to put some
primer surfacer on. But first, let’s get it mixed. OK, we are going to
go ahead and mix up some epoxy primer for
this particular job, we’re going to use Shopline. And they way this
mixes, you always want to make sure you look
at your procedure pages, and they’ll give you
the product information and see what the
recommendations are. Because on epoxies,
a lot of times there’s an induction time. On this particular product,
if you look on here, it says the induction time
is 15 induction time period. So you got to wait
for 15 minutes after they have
been mixed together. This is kind of like , if
you think of it as they have to kind of get to know each
other a little bit before they bond. So if it’s just epoxies. There’s not a lot of
products that have that. The mixing ratio on
this, so what that means is two parts of
epoxy and we’re going to use one part of a
hardener, a catalyst. This happens to use 3770. We don’t need a
whole lot of epoxy, so we’re just going to
use a small mixing cup and mix up a small amount. And what the epoxy is for,
it’s for a couple reasons. For corrosion resistance
to prevent rust and things like that, epoxy works
real well for that. And also it is real
good for adhesion. It sticks good to metal. And on other things, the surface
sticks good to the epoxy. So it serves several purposes. So I’m just going to go
and mix up a little bit. If you look on here, the
ratios are on there for you. So you find where it says
2 to 1 Right here’s 2 to 1. So you mix up however
much you’re needing. So I’m going to mix up to 2
primer and then 2 catalyst. On some of the cants,
it will tell you 2 to 1. It says it right here. I’ve also seen some cans
it doesn’t say that. So it’s always a good idea
to have your procedure pages nearby where you
can look at that. They also tell
you about how long the flash time in between codes. For this job, we’re going
to put on two coats of this. And another thing
about epoxy is it has a 72-hour window
that you can come back and you can spray your
base coat or your surfacer or whatever you’re
putting on top of this. You have 72 hours. And like a lot of
products, it’s just a 24 hour with a Shopline
or PPG line, I don’t know. Some of the others may be
a little bit different. But you do, that’s
good with this. See, it’s not a lot. Just enough to
cover that one spot. And I’ll go ahead
and mix this up. And now, we have to let it
sit for 15 minutes, that 15 minute conduction time. I can say, this is usually
just with the epoxy primers. That you’ll have to do
that step and let it set. So we’ll let that
sit for 15 minutes. Put it in again, and
we’ll be ready to spray. OK, we’ve mixed up
our epoxy primer and let it sit for 15 minutes. And we’re going to use
the 3M cups and liners. It works real well for this. And we’re going strain it. And usually, whenever
I’m straining my primers, I use at least one strainer,
sometimes I used two. But usually with the Paint
and Clears, I use two. So I’m going to use
strand with this. Just pour it there. The top sets on it, and also
the way these are designed, there’s actually another
strainer on here. I hope you enjoyed this
lesson on epoxy primer. If you did, be sure to give us
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100 Replies to “Epoxy Primer vs Self Etch Primer for Bare Metal”

  1. Hey Donnie, can I strip a motorcycle tank to bare metal, sand it with 80/200/800, put some epoxy primer and call it a day? I want to get that cafe racer bare metal look but I don't know if I should be doing something else to protect the tank. Cheers.

  2. I used epoxy primer on my Ford van and the rust came through it even though i went down to bare metal. Epoxy goes on thick like syrup so it leaves a poor surface for a top job.
    Etch primer lays dead flat, I sprayed a BMW with eopxy and not one bit of rust came through? Is it the car or the primer that stopped it,I dont know but prefer etch primer

  3. Can you tell us a bit more about the DTM primer/sealer? I have a can of it.

    Also, I checked the can and the documentation and there's no window specified. Any reasonable estimates? It says I can sand after 50 minutes, but it may take a few days before I can topcoat.

  4. I working on a beat up 92 Ford F250, finished body work on the hood and applied epoxy primer.  Wouldn't you know it I missed a small ding, can I apply bondo directly over the epoxy?  Also I intend to apply a high build primer, how long can the epoxy primer sit before applying the high build primer?  

  5. thats where i get confused i have some clean metal spots and black rust spots also…after wax and grease remover what should be done to the bare metal…should it be prepped or just hit it with epoxy

  6. Thanks for the video.
    I have one question. Do I need Epoxy Primer or Self Etch Primer for aluminum metal, my morocycle foot pegs for instans?

    Thanks again.

  7. hey there
    i just cant understand why its not possible to apply body filler to etch primer? what happens when you do?
    is it just a question of "bad adhesion" or dose it react somehow with the etch primer? cos to me it sounds even worse to apply filler direct to metal since its a poros material and simply the moisture in the air would get trapped under the filler as well… in my mind you need to apply something that chemicaly merges with the metal ( like acid helps etch primer do ) or something that transports ANY moisture to the surface or otherwise away from the metal. 
    good vids by the way this is not critic just woundering

  8. Very good video.

    I use Epoxy all the time and here's a few things to consider as well.

    I see your catalyst is nice and liquid, thinning down the final mix to a sprayable consistency.

    My epoxy catalyst is THICK. The ratio on the Nova 3000 I like to use is 4 parts epoxy and one part catalyst, after induction time the mix is THICK.

    I wouldn't even consider pouring that down my gun, it just won't shoot no matter how big a nozzle I use so I have to thin it down. Ask me how I know.

    Tip : When you buy epoxy, inquire how think the catalyst is. In order to shoot paint or anything with a gun it needs to be thin, almost like milk. So if the catalyst doesn't act as a thinner, you NEED TO BUY EPOXY THINNER, any all purpose thinner will not work, some will even sort of coagulate your epoxy after a few minutes and good luck cleaning that out of your gun, you need a specialized thinner.

    Personally I like to thin quite a lot and shoot out of a 1.8 nozzle on the HVLP gun.

    If you have to thin your epoxy primer, wait AFTER induction time. So you wait your 15 or so minutes, stir it up a bit and pour down the thinner until desired consistency.

    Second thing is that epoxy doesn't sand very well in my experience. Some primers sand better when completely dry (72+ hours) but breaking the surface of the primer with sand paper is annoying and can gum up the paper real fast.

  9. I have slivers of bare metal that need to etch primed that are enclosed by sanded basecoat.  Can I get etch overspray onto the sanded basecoat without negative effects?  If not, how would I go about prepping these areas?

  10. Technical Noob Question: What about both? I noticed you stressed the word "OR" when talking about self-etch and epoxy, but can you put self-etch down and then epoxy over it for like super-awesome corrosion control? Please excuse my naivete, I really don't know what I am doing and thought I would ask. Thank you for your time and pointers.

  11. How do you clean the steel panels prior to applying epoxy? Do you use hydrochloric acid? Some people have mentioned corrosion breaking through epoxy. Naked hands are a no-no, but perhaps a acid application followed by water and degreaser would solve that issue. What do you think?

  12. Can you wet sand self etch primer if you used it in a circular area of just about one inch long? or just sand it with with no water?

  13. you sound like you prefer Epoxy… i'm planning to paint an expensive and difficult to remove part of my bike… the back branch, its casted aluminum, so i want to primer and paint once and for all… so epoxy primer… am i right?

  14. I want to paint my factory paint job a new color. I've watched a lot of videos on how to get a car ready for paint. I wanted to know? After, I do my body work like bondo, scuff up the whole car, then spray a 2k urethane primer surfacer, and block sand it with guide coat and when the whole car is ready for paint. Can I spray an epoxy primer on top of the 2k primer surfacer and leave it like that for a month till I'm ready to paint it? Of Course, when I'm ready to paint it I will scuff up the epoxy primer then paint my base coat followed by a clear coat. I want to do this in a 2 step process, because I'm going to pay a shop to spray the car for me twice once for primer and then again for the paint and clearcoat. But I'm going to do all the body and prep work myself so I can save a few dollars. Thanks for you time and I would appreciate any tips and help on this matter. ~Sam.

  15. I'm attempting my first restoration and this video really helped me chose the first coat of paint on the bare metal!

  16. Why would anybody use self etch if you cant put filler over it? Your metal work would have to be perfect with all the fill done before self etch sanding it back down to metal if there are imperfections that filler primer cant take care of, just saying.

  17. I want to paint a Brass HO scale steam locomotive and was going to use self etching primer for it. I won't be using any filler or anything but was wondering if this is overkill?

  18. Hey, was wondering why you don't use the 3m mixing insert instead of the mixing cup? Isn't the strainer on the Pps cup good enough? I ask because this makes more trash and you lose paint do to stiction on the mixing cup. I use the 3m pps cups and gun. Where do you buy your paint supply's?

  19. @DIY Auto Body and Paint 2 years later to my last comment,i can reveal that i sprayed a metal drum BBQ in my back yard with both epoxy and etch primer in 2 seperate halves on the drum lid and 2 years later the etch primer wins,no rust coming through wheras the epoxy has rusted.
    The BBQ drum was left outside in all wetahers totally unprotected

  20. @DIY Auto Body and Paint Do you know if ZINC primer is better than etch or epoxy? and if the primer was applied by hand brush instead or sprayed would it perform better as more product is going on?

  21. Kudos! Question. When is the right situation to apply a DTM primer? I am guessing that it is for when your primer will also cover a painted surface and you do not want the acidity of an etching primer to lift the existing paint?

  22. would it provide more corrosion resistance if you lay down Self Etch>2 thin layers of vinyl primer to prepare for next step WHICH IS> epoxy primer. You can't put epoxy on wet etch primer cuz it won't let it do it's job and form the protective film.

  23. One of my first jobs was to paint big I-beams that had been fabricated for buildings and bridge work. The first day, knowing nothing about paints, I was given an airless and told to paint the metal, which had been blasted. I did it, and at quitting time, the boss said I did a good job, and to be there earlier tomorrow as he had a lot more to paint. When I came in the next day, he asked me did I clean out the airless unit. I said no. He told me that I wasn't to blame as I told him I didn't know anything about paint. We had to replace the hose, but the pump and gun we soaked in lacquer thinner and it cleaned it out very well. He said he woke up about 2 am and thought about it, but figured if I didn't clean it, there was no one to blame but himself.
    I worked for that guy for 13 years, he was a great owner/boss.

  24. can you apply paint sealant over epoxy primer ? Also i'm kinda confused but after applying paint sealant can you leave it and paint over it?

  25. I'm one of use por-15 for my undercarriage do I need primer or can I just put it on that way by itself and maybe later spray over it thank you again

  26. I HAVE FOUND THE ULTIMATE IN RUST PREVENTION AND PROTECTION,its a group of paints called COLD GALVANSING PAINT,its like galvanising your car body,infact painted on its more protective than anything thats been hot dipped in a galvanising factory. Ive left steel outside in the rain and damp painted with this product and i cant get it to rust 🙂 even hosed it down every day with water,still no rust, Google brands such as ZG90 and ZINGA, on average it will protect for about 5 years as it is just left outside,but overcoat it with a proper top coat and that changes to about 30 years.
    Its amazing,ive researched rust and prevention of it for 6 months and ive found this to be serious overkill protection for cars,but to me theres no such thing as overkill whn it comes to rust prevention.
    This type of paint is about 98% Zinc, thats the secret to the rust not starting,the zinc sacrifices itself to protect the underlying steel,its amazing, even the tin of paint is very heavy because of the high zinc content.
    Its weather resistant,salt resistant,waterproof etc,its used on offshore oil rig legs that are submerged under water, that how good it is,one coat is all that is needed,its also available in spray form.
    I personally have used ZG90 made by ACTION CANS,its truly amazing,i can say goodbye to rust now forever,no more redoos or resprays due to rust coming through, cut it all out, weld in new panels, then paint the ZG90 on the bare steel, then prime,basecoat,then clear, job done, rust wont even show in the slightest for 30 years

  27. Hi Donny. Thank you so much. This video explained a lot and cleared my confusion. Such a simple video, pack with high-end info. Thank heaps! Kim.

  28. I saw your video and it was very informative. I am wondering if I can use the epoxy on a collectable loggers hand saw. I am a spray paint artist and received a request to do a cabin and mountain scene and new york skyline on stainless steel. Ive never painted on stainless steel before the dimensions of the 3 saws are 5 foot long 6 in tall in center, 5 inches tall by the handle at the other end 1 1/2 ' tall. That is the biggest one. The smallest one is 29 inches long and 4 inches center. Any kind of direction would be appreciated.

  29. State there's three options:  epoxy, self-etching, & DTM.  How does the primer-surfacer & sealer apply to priming?

  30. Where can I get those gloves? Very good video. I was needing to learn about epoxy as I'm doing a 56 belair. Thanks

  31. After applying phosphourus to bare metal do I sand the phosphorus off then apply epoxy primer or just apply epoxy over the proposed?

  32. If i cleaned magnesium properly could i use 2k epoxy on it and not worry about it lifting off from escaping gasses getting though the magnesium/ aluminium?

  33. Great video thanks is it ok to put one coat of self 2k etch primer on then a couple of coats of epoxy on top of the self etch both panels I'm prepin have been no blasted back to bare metal I've only ever used self etch in past found it fantastic but I'd like to try epoxy on top of the self etch as a added bonus wat would you recon thanks

  34. really hoping someone, maybe even Donnie can answer this for me as I cant seem to find anything on my specific situation. I have sanded down the factory paint using 180 grit sandpaper and have taken care of the bondo/bodywork (taking those areas down to bare metal before applying bodyfiller). Small areas throughout the body work have been sanded down to bare metal. I was told by my epoxy primer/sealer manufacturer to reduce the epoxy and spray it as a sealer but It may take me awhile to be able to fully spray those panels due to cold temps here still. So my question is can I use rattle can self etch on those bare metal spots and shoot the epoxy sealer directly over that and the rest of my scuffed original paint or will there be problems?. I keep reading not to shoot epoxy over self etch. Any help from anyone would be greatly appreciated.

  35. I am Restoring a classic Peugeot 404. It’s in the body shop now. Must I go to bare metal on the whole car to get a show car finish?

  36. Can I use epoxy primer on water cooled bike engine? My question is: What's the best primer for aluminium that can get hot?

  37. wow really good, informative video man, told me exactly what i needed to know, thanks man

  38. On a surface that has rusted and been blasted or DA’d how should the metal be handled and cleaned to ensure adhesion of the primer? And what kind of window?

  39. They had me 'till the end, when he finished mixing the epoxy the video cut to the ending sequence and you don't get to see how the product goes on, but i suppose its not necessary to see a spray coat lol

  40. One question which is better way put epoxy primer first at the metal before put filler or after put the filler and sand it all area repair with plastic filler then put epoxy primer on the filler and metal and after dry put primer ????????

  41. Which one you think is the best for Aluminium and which is which is the most resistant heat. Im trying to paint my car engine gearbox and i confused what is the best for last long. Thanks and nice explanation.

  42. I am a little confused. "Primer surfacer should not be applied directly to bare metal". Isn't primer is a chemical that designed to be applied to a bare metal before painting it? Thank you in advance!

  43. Thanks brother great video as usual, my issue is I have a small area where I sanded through you told me to use etch primer, then primer surfacer, then block with a 320… every time I block with 320 it takes the primer surfacer and etch primer off again… I used 3 coats of primer surfacer and a light coat of etched primer. I do have epoxy primer (beige color) should I try that over the bare metal then primer surfacer then block with 320 to see if I get a different result?? This is new to me and I’m NOT giving up help me please

  44. Newbie question here…
    I bought 5star #5451 highbuild 2k primer and realized I may hit some metal seeing that prior owner used mystery paint and looks like he hand rolled the paint on haha. I’ve seen the prices of some etching primers and I’ve seen some $20 SEM or Upol aerosal self etching primers. Can I use aerosal self etching primer on exposed metal and then spray my urethane primer? Will it react and mess everything up?

  45. Awesome video man and very informative! I am clear coating a bare metal garden bench to keep that industrial look. I have bought 2k clear Matt to finish it off, if I use epoxy primer on the bare metal and then 2k clear over that, will it work nicely?

  46. Thanks, very helpful.
    Unfortunately there are many really pertinent questions asked here but no responses, that's very frustrating.

  47. As I see others saying in the comments, this is the most comprehensive video on primers on youtube. Good job and thank you!!

  48. I applied primer on my entire hood but the spots where i had bare metal still showing after primer, base coat and clear coat… what did i do wrong? should i have sand down to bare metal the entire hood?

  49. sanded down some indoor hand railing down to the metal, someone told me to use etching primer over other primer because the paint will adhere better on the etching primer, the railing gets used alot on a daily basis. Other people told me it don't make a difference what type of primer, any info would be very helpful

  50. What do you think about painting calipers all sandblasted, no cylinders, seals etc… I know powder coating is best, but as a painter myself i would like to save some pesos $$$, by shooting them with expoxy primer and eurethane , any thought , do you think it will last….?

  51. If dealing with a frame that was blasted to bare metal. Is it good to etch the metal with etching solvent like POR15 metal prep and then paint any kind of paint ment for frames and stuff , like eastwood

  52. If dealing with a frame that was blasted to bare metal. Is it good to etch the metal with etching solvent like POR15 metal prep and then paint any kind of paint ment for frames and stuff , like eastwood

  53. If dealing with a frame that was blasted to bare metal. Is it good to etch the metal with etching solvent like POR15 metal prep and then paint any kind of paint ment for frames and stuff , like eastwood

  54. If dealing with a frame that was blasted to bare metal. Is it good to etch the metal with etching solvent like POR15 metal prep and then paint any kind of paint ment for frames and stuff , like eastwood

  55. If dealing with a frame that was blasted to bare metal. Is it good to etch the metal with etching solvent like POR15 metal prep and then paint any kind of paint ment for frames and stuff , like eastwood

  56. if im building a caravan sort of construction, with spray foam being applied to sheet aluminium, what would be the best way to prime?

  57. Why would you ever need to use self-etching primer over a painted surface that's already adhered to the metal? Couldn't you just then spray a color coat after light sanding?

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