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  #16 (permalink)  
Old 02-07-2012, 06:46 PM
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I thought you had to put etch down first on bare metal??
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Old 02-07-2012, 11:58 PM
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Depending on the system you are using etch is not a requirement, you just need a DTM (direct to metal) primer. My preference is epoxy, not only does it stick like crazy it also has enough body to do some filling and most important and unlike any other primer it is a 100% moisture barrier. Once coated in epoxy primer you will have no problem with surface rust even if you leave it out in the rain for a year. This also means that once the car is painted if you get a scratch or chip in the topcoat the steel is still protected.

Actually I like to use epoxy under the filler as well as on top because filler is like a sponge, with epoxy under the filler even a deep scratch that gets down to the filler won't lead to a rust spot.

Etch primer is not compatible with all fillers but epoxy does not have that problem, in my mind it's the best insurance you can put down for your paint job. As for a brand, like many others here I like SPI, you can get it mail order, it sprays nice, it sets hard and it sands easier than many other epoxies, plus it's less expensive than many of the name brands.

If it were my project, I would get rid of the etch, spray on two coats of epoxy and then a 2k urethane and start blocking. And did I mention that epoxy thineed about 10% makes a great sealer before your topcoat?

It's good stuff.
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Old 02-08-2012, 03:55 AM
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Thanks I am going to let my husband know. I can't do anything on drivers side with epoxy first before filler. But I cando that on the other side.

We are painting the car jet black with pearl white light ghost flames on hood and down the front fender a little. None of the body trim is going back on it.

So I really want the paint to last. Not going to be an easy fix if something happens...

Thanks again!!!!
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Old 02-08-2012, 05:49 AM
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Quote:
Originally Posted by glessen
I thought you had to put etch down first on bare metal??
Yes,but.....
Bondo will not stick well to etch primer it has to be sanded off,filler goes directly on bare metal then then etch is reapplied after sanding filler. I have a couple of horror stories about using etch with filler on top....and a whole days work coming off in one sheet with an air blower and a putty knife....
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Old 02-10-2012, 04:14 PM
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Ok now that I have heard all the stories on the etching primer. I am sanding the car down so my husband can apply the epoxy primer instead. But why in Gods name is the primer gumming up on the sand paper??? I am about to pull my hair out.

I want the car to be ready so the epoxy sticks good. But to get the etch off oh my flipping god. What am I doing wrong?
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Old 02-10-2012, 09:16 PM
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what 39 hemi said...x2
If it were my project, I would get rid of the etch, spray on two coats of epoxy and then a 2k urethane and start blocking. And did I mention that epoxy thineed about 10% makes a great sealer before your topcoat.

i know it may be tempting to hurry up.. but, paint especially black, is nothing compared to the quality body under it.. grab a D/A and some 150 -180 and go over everything, remove the etch ...then 2 coats of epoxy, folllowed the next day with good 2k, I use omni..for a sanding primer..then let it sit for a couple weeks..or pull it out in the sun, but let it sit !
no sanding between epoxy and 2k, unless you cant stand it, then a red or gray scotchbrite is plenty. block the 2k with 220 or finer lightly dry, use a guide coat..., if you are happy with the body..move on to 320, 360, 400, wet..then seal and paint...

IF !!! while you are sanding off the etch, and you are not happy with the bodywork..you might consider spraying a coat or 2 of feather fill...http://www.evercoat.com/productCategory.aspx?cat=10
it's sprayable bondo,,,

be patient, this is ony 1/2 black and it took forever!


Last edited by skip99; 02-10-2012 at 09:30 PM.
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Old 02-11-2012, 05:00 AM
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Quote:
Originally Posted by glessen
Ok now that I have heard all the stories on the etching primer. I am sanding the car down so my husband can apply the epoxy primer instead. But why in Gods name is the primer gumming up on the sand paper??? I am about to pull my hair out.

I want the car to be ready so the epoxy sticks good. But to get the etch off oh my flipping god. What am I doing wrong?
It sounds like you may have forgot to add the activator,try washing it off with lacquer thinner...it'll take a lot of rags and be sure to wear rubber gloves ,it absorbs through your skin.....Concider yourself very lucky you found this out now and not later on after many more hours were spent...
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Old 02-11-2012, 05:33 AM
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Quote:
Originally Posted by glessen
I thought you had to put etch down first on bare metal??
To answer your original question, it appears that the filler absorbed the primer, nothing out of the ordinary there. Had you used 2k primer or epoxy primer the filler would be sealed and the next coat of primer would have covered it.


Etch primer has no place in today's world IMHO. Epoxy is superior.

Do yourself a large favor and call SPI @ 706781-2220 and get their epoxy and 2k primer. When you are ready, use their clear too. (free shipping! & best customer service you have ever experienced)

By doing this you will have excellent products at a very fair price, and they will work for you .

Like a number of others have said, most likely you need to remove the etch primer if you want the paint job to last for the long haul.

MAYBE the product you used is compatible with the filler you covered it with and the product line has a 2k primer that will cover the etch is the other option, Google the product line, read the TDS for each product and follow it and you might not have a problem.

If you are a Chinese car lot (lol @ dbm) and have no conscience leave the etch, put some rustoleum over it and sell it before it all fails at the car wash.
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Old 02-12-2012, 08:53 PM
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Quote:
Originally Posted by skip99
what 39 hemi said...x2
If it were my project, I would get rid of the etch, spray on two coats of epoxy and then a 2k urethane and start blocking. And did I mention that epoxy thineed about 10% makes a great sealer before your topcoat.

i know it may be tempting to hurry up.. but, paint especially black, is nothing compared to the quality body under it.. grab a D/A and some 150 -180 and go over everything, remove the etch ...then 2 coats of epoxy, folllowed the next day with good 2k, I use omni..for a sanding primer..then let it sit for a couple weeks..or pull it out in the sun, but let it sit !
no sanding between epoxy and 2k, unless you cant stand it, then a red or gray scotchbrite is plenty. block the 2k with 220 or finer lightly dry, use a guide coat..., if you are happy with the body..move on to 320, 360, 400, wet..then seal and paint...

IF !!! while you are sanding off the etch, and you are not happy with the bodywork..you might consider spraying a coat or 2 of feather fill...http://www.evercoat.com/productCategory.aspx?cat=10
it's sprayable bondo,,,

be patient, this is ony 1/2 black and it took forever!

Do you have any pictures of the door jambs on that two tone paint job? Im doing a similar project and wondering how to stop overspray from getting into the door jamps (which I also two toned) when shooting the outside?
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Old 02-13-2012, 09:17 AM
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figure out where the lines will be , spray the jambs and clear, then mask the jambs and back tape the edge of the jamb, that means spray the jambs so color just gets onto the outside edge, then when spraying the outside, just start rolling the edg of the tape back into the jamb with each coat, and the let the clear overlap into the jamb as much as you can.. the dry overspray will come out with the buff. OR..do it just the opposite, spray the outside, then backmask the edges and spray the jambs, you can pretty much hardline (with fineline 3m blue tape)the door edge, but the quarter jambs need to be soft masked to look seamless.
they make aperature tape but its expensive,


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Old 02-13-2012, 04:44 PM
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hmmm...
I know refinish suppliers keep coming up with new products all the time. And we hope they get better as well, but the refinish game, changes are often prompted by government requirements.

In my definition, etching primer is used on bare metal. It serves two purposes, adhesion to the metal and rust prevention. It contains zinc, which is a sacrificial material. It will oxidize before the metal, and can prevent rust by doing so.

In my shop, we always apply etch primer to bare metal before body filler. The etching primer we use must be coated with a 2 part urethane primer, since polyester and other finishes will not work.

After the filler work is done, any bare metal is again coated with a very light coat of etching primer, then urethane is applied. If the filler is close to proper contour, the urethane can be applied as a surfacer (thicker) and blocked out. Or, spray polyester primer can be applied.

We usually cut filler with 40 grit, but often we start with 80. We finish cutting filler with 120 and sometimes 180 grit. The closer the filler is, the less time and money will be spent on primer/surfacer.

Remember, once metal shows through, you can't cut it any lower. The rule "sand until the highs meet the lows" is good, but metal doesn't cut with sandpaper. When you start to see metal showing, it's time to massage it down with a mallet or hammer... or fill the lows again.
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Old 02-19-2012, 10:09 PM
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I agree with the first guys epoxy primer than 2k high build primer, block sand. If the first primer is gumming the paper,wash it off with lacquer thinner and start over or it will haunt you forever.
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Old 02-20-2012, 10:12 AM
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The problem with epoxy primer is catalyzation. If you use any epoxy primer, follow label instructions carefully, and do anything else you can to promote proper hardening. Letting the mixed primer sit and begin to crosslink (induction) is worth doing.

We use a 60 second solvent test on all substrates. OEM finishes that are unaffected by the 60 second test can be trusted. Epoxy primer that doesn't pass can't be trusted. To do the test, we fold up a paper towel, soak it with lacquer thinner and hold it on the surface. If there is no, or very little effect, it passes.

We don't use epoxy primer. If it doesn't harden properly, it's no better than old time lacquer primer.
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Old 02-22-2012, 06:03 AM
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epoxy first has become the norm in custom and high end work. it is best for adhesion and corrosion resistance. be advised there are some epoxies out there that are not a true epoxy. you get what you pay for.
etch primer was pushed in the 70's because of all the peelers. they were blasted with acrylic and etched . required no sanding or taking apart. etch will absorb moisture just as an old lacquer primer will .it is not a primer surfacer and is to be put on thin. not really any place for it any more. the failure rates on etch got too high.
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