Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Body - Exterior> Epoxy vs Urethane Primer
User Name
Password
lost password?   |   register now

Thread: Epoxy vs Urethane Primer Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
11-23-2008 05:50 PM
FJ Cruiser Guy
What do you use during metal work?

I used a DTM Epoxy primer on my truck after complete sand blast. It worked very well. Question is, what do I spray on areas where I am now cutting and patching rust spots? This is pure metal work right now, no filler. Cut rust out and weld patch panels/pieces back. I need something that is easy ie. rattle can, while working on metal bc I can not be moving back and forth to the spray booth and spraying two part primers.
09-22-2007 05:10 AM
helicfii Thanks. The prices I've been quoted for plastic blast media are insane - but it appears to be the best blast media choice for an old car.

Also- I am completely sold on laying down epoxy without an acid wash, then doing the bodywork over that. In the past, I have carved filler out of bare metal many times only to find rust under the bondo. It's amazing that people didn't think of bondo over epoxy back then...
09-21-2007 06:58 AM
wildman1932 My two cents, after 40 years of restoration work.
Sand blast, plastic blast or sand with 80 or rougher.
I do not use an acid wash next. The phosphate coating is great if your are doing metal work for extended time open time, then sand it all off. The best surface for epoxy is bare metal.
Next a good epoxy. This coating is only to protect the metal. Not for any kind of build up.
Next any kind of bondo work that you will do.
Then comes the urethane building surfacer or (spray poly)
Spray poly is not a primer surfacer. It is a spray-able body filler, the will be covered over later with primer surfacer.
I tried to make this as short and sweet as possible.
Dave Tallant Hot Rod Shop KC Mo
09-21-2007 06:38 AM
helicfii I had no idea that you could flow cavity wax. It makes sense to apply it after the paint is done.

I'll let you guys know how it goes after I start stripping the individual panels with aircraft stripper & prep then epoxy prime.

Thanks for the info.
09-21-2007 05:24 AM
baddbob For the interior of the doors clean them as best you can, apply epoxy primer to any areas that can be cleaned well, treat any areas that can't be cleaned well with a cavity wax like 3M Rustfighter. I usually tape the drain holes shut wo the coating doesn't run out and let the seams soak and fill with the waxy coating then pull the tape a few days later and open up the drains. The cavity wax should be applied after your paint work is done to avoid paint contamination.
09-20-2007 05:52 PM
helicfii Good advice.

Since I'm used to only painting frames and motorcycle gas tanks (read: easy), what do you guys do to strip and prime the inside of doors? Do you slosh epoxy in there, or what? It just seems like those kind of spaces are going to be impossible to clean 100% and prime 100%.

If I am going to go through all this headache, I just want to make sure that this poor little car doesn't have to go through this again for at least another 50 years!

I just want to get every last bit of corrosion out for good...?
09-20-2007 08:17 AM
MARTINSR If I can add something, forgive me if it has been mentioned I only skimmed the thread. Do not strip this car completely at one time. Strip a panel or two MAX then prep and get them in primer before moving on to another panel. Stripping a complete car is a HUGE undertaking and unless you have a lot of time, room and experiance a guy is usually pretty overwhelmed by the job.

Brian
09-20-2007 07:18 AM
helicfii Thanks, man- that was just what I needed.
09-20-2007 05:12 AM
baddbob Sometimes I spread the seams open between the spotwelds and use a spot blaster to get as much corrosion out as possible, then epoxy prime, apply a urethane seam sealer and close them back up with hammer and dolly. This works well on accessable areas. It's also very important to treat these seams from the backside with cavity wax if possible. Bottom line is, trapped acid in these seams is worse than leaving some light corrosion and sealing it off from both sides. Cut the oxygen supply off and the oxidation will stop. In cases where the rust is severe within the seams you should section that area out, remove the corrosion and weld it back together or make a replacement piece.
A quality epoxy will have a good amount of Zinc Phosphate in it for corrosion resistance.
09-19-2007 08:00 PM
helicfii Thanks for the input.

Yeah- the more I read, the more I am shying away from sandblasting any flat panels.

If I go with chemical stripping & sanding, then go straight to epoxy, should I be concerned about the seams in the body? As you probably know, British cars are notorious for having a lot of seams where certain permanent body panels meet (front valance, rear valence, turtle deck, etc...). This is why I was leaning towards an acid wash- so that I would get some protection down in the nooks and crannies (and there are a lot of them!) in this old car.

My biggest concern is getting some protection in those areas that I will not be able to reach with sanding- I am expecting that there will be a small amount of surface rust in those seams that I simply will not be able to reach.

What do you think- should I just flood those small seams with a zinc chromate primer before applying epoxy???
09-19-2007 07:05 PM
baddbob Sandblast your jambs, floor, engine compartment, window openings, but don't sandblast the exterior surfaces unless you have experience and can control the blaster for no metal warpage. A 67 Triumph is a tiny car and it wouldn't take very long to strip the exterior with chemical stripper, a razor blade scraper, sanding or a combination of all. Your metal should have a blasted texture or be sanded with 80 grit prior to applying any epoxy. Clean it well with wax and grease remover. Once the parts are in epoxy you can work any damaged areas at your own pace. Fillers can be applied to epoxy primer without the need for sanding if done within the epoxy's recoat window-but after the recoat window is up and the epoxy reaches full cure you'll need to scuff it with 180 grit for texture before any fillers are applied. Read the tech sheets on the primer you are using and if there's any question contact the manufacturer. Starting with a quality epoxy over clean and textured bare metal is the foundation for a job that will outlast you and I.

You've got a few choices on primer surfacers, polyester for heavy fill work, urethane, and epoxy hybrid types. Stay away from lacquer 1K surfacers. Also stay away from the acid wash products-they are not needed when using quality epoxy and can make for some mysterious problems down the road if not used correctly. Most acid etch primers should not be applied over sandblasted metal.
09-19-2007 12:04 PM
helicfii BondoKing-

Thanks for all the great info (and the links- I guess this is a subject that gets beat to death!). This is making a lot more sense to me now.

If I am correct, it sounds like I can safely do this:

1. Sand blast the entire car
2. Immediately acid wash each part after blasting
3. Clean with Prep Solvent
4. Apply Epoxy Primer
5. Scuff areas for filler
6. Body filler & sand
7. Urethane build primer & sand
8. base coats (with or without sanding)
9. clear coats (with or without sanding)

One BIG question about dealing with a sand-blasted car:

After blasting I will have a lot of blast media residue to deal with. Since the metal will begin rusting right away, I probably don't want to rinse/clean the body with water. Obviously, compressed air won't blow all the residue away. If I just spray the acid wash right onto the bare metal that has blasting residue on it, when I go to clean with prep solvent (much later, but just before applying the epoxy), will the prep-solvent and wiping take care of all the blast residue?

I just don't want to paint over blast residue, and I don't want to rinse the car with water...how is this generally handled? Or am I worrying too much (impossible, right?)?

And thanks for everything.
09-19-2007 05:13 AM
jcclark
Quote:
Originally Posted by BondoKing
I as well as countless others on this boards and others I frequent use these products and never have problems...Matthew
He means only with the products he doesn't have problems,
But he has problems, big, big problems!!!!.LOL
(and I may be one of them )
09-19-2007 12:01 AM
BondoKing Dave the best bet is epoxy primer.. People will debate till the end of time whether its best to use an acid etch, then epoxy , or epoxy only, or acid etch then 2k etc etc etc..

For top notch work, IMO, using epoxy, then your 2k build primer for blocking is the only way to go.. Acid etch is yester years technology and while it was all good back in the day.. back in the day is gone..

I would also recommend that you strip that paint job.. start off with epoxy and work your way up.. I was not alive in 67, but I would assume its lacquer..

When you read of someone working off of an existing paint job and being told its okay to do that , they are speaking of urethanes and you could do the same with acrylic enamel paints, that have one paint job on them, not multiples..

Lacquer is porous.. Its a sponge ( read acid etch.. is a lacquer primer with acid content is all.. read dont use!!)..
If your paint job is lacquer as i assume, then you dont want that sponge underneath a fresh job.. Plus you dont know whats underneath a paint job that old.. You would be surprised what you will find often..


You will hear everyone talking about 2k.. that is just a name we use for urethane primers.. epoxy is called epoxy and base coat and clear are called what they are..

i would strongly suggest you start fresh and do it right... By that I mean stripping it and starting with epoxy..

Epoxy is the same resins as Ecoat.. the stuff they dip the cars in at the factory.. Only difference is solvencys between the 2.. One is bake only, while the other can air dry (epoxy)..

A little reading infor for you as well

etch vs epoxy

epoxy on bare metal

Bare metal prep

tac rag info


This should get you going.. I am sure someone else will chime in when they read this on Wed..
09-18-2007 10:56 PM
helicfii
Old thread, I realize, but...

I am new to the forum. I am preparing to do all the stripping, bodywork, prep and painting of my 1967 Triumph TR-4A (Car). In years past (25 years ago), I worked with laquer on motorcycles. A lot seems to have changed since then...

I have read elsewhere that if the original paint on a car is in very good condition (and mine is- it has never been repainted), that the original paint makes for an excellent base to work on- that it is either undesirable or unnecessary to completely strip the entire car if there are no extra layers of paint on it.

What I cannot find an answer to is this:

There are some portions of the car that I will be sandblasting (engine compartment and interior) that need stripping. There are some portions that will require minor dent repair, some that will require interior panel replacement. All of the modern primers seem to have different limitations- one is for bare metal, and another is for primed metal, another for painted metal...my car will have all 3 surfaces!

Using a bc/cc as a finish, and working backwards, I am having a lot of trouble coming up with a step-by-step plan for when to prime, when to bodywork, when to use a filler primer, etc... I am also concerned about having to use different primers on different parts of the car, and how all those different products overlapping might cause hreadaches later. I will also need to use something like Oxysolve after sandblasting in order to keep the bare metal from rusting until I can either prime it or put filler in it. Some have opined that the use of this product under fillers is a bad idea.

Is there a thread in this forum that gives an example as far as a plan for how to deal with these issues, and which order to proceed if I am trying not to strip the entire car and end up with bc/cc?

Anything will be much appreciated. Thank you.

-Dave
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -6. The time now is 05:16 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.