Which epoxy primer is best? [Archive] - Team Camaro Tech

: Which epoxy primer is best?


67ss350rs
Nov 19th, 06, 05:47 PM
I'm getting ready to shoot the entire car with epoxy primer, which epoxy works the best for you? Thanks for the help

Satatic
Nov 19th, 06, 07:09 PM
I love the SPI epoxy. When you sand it it turns to dust like high build primer. Great for filler over epoxy. The PPG stuff I used before just clumped on the paper and ruined it after a few strokes.

67CAMAROSS
Nov 19th, 06, 07:49 PM
i have been useing transtar so far so good

Sid69Z's
Nov 19th, 06, 08:04 PM
Another vote for SPI (http://www.southernpolyurethanes.com/homepage.htm) :thumbsup:

Sprays great, sands great, and you can't beat the price for a top quality product! You can read some more about it Here (http://spi.forumup.org/viewforum.php?f=4&mforum=spi&sid=d3bccc899b098638c922838d18f658c5)

camaro41701
Nov 19th, 06, 09:23 PM
I do 3-4 camaros a year. I talked to dupont & ppg reps about thier epoxies.They both told me that if the surface had not been sanblasted or rougher to use etch primer.I have used epoxies for years and had a few come back with problems.The reps came out to inspect them and thats when they told me to use etching primer.

c1run1
Nov 19th, 06, 11:11 PM
anytime your working with bare sheet metal on a large surface to use an etching primer first . Then epoxy it . : )

sevt_chevelle
Nov 20th, 06, 05:31 PM
Not all epoxies need etch under them. SPI and valspar and am pretty darn sure Spies does as well, clearly stat that etch is NOT to be used with epoxy as they react. This reaction causes paint failure.

Ive had several PPG reps say NOT to use etch over sandblasted metal because it will puddle in the pit and not dry. Then you come back over it with more reducers, paints, it seals off that undried acid from the etch forming rust bubbles.

IMO PPG can not figure out the epoxy game since they stopped making the old DP epoxy and replaced it with that crap they call DPLF. If you look at the DPLF tech sheets from years past you can see how they kept flip flopping back and forth on the recommendations.
Am sorry but PPG doesnt have a clue when it comes to epoxy primer, and am big PPG fan.

Another vote for SPI, it makes the PPG and Dupont epoxy look flat out stupid...Eric

tired68
Nov 20th, 06, 08:37 PM
IMO PPG can not figure out the epoxy game since they stopped making the old DP epoxy and replaced it with that crap they call DPLF. ~~
Another vote for SPI, it makes the PPG and Dupont epoxy look flat out stupid...Eric



So, lets see. A company that specializes in coatings and chemicals having a market cap of 10-3/4 Billion dollars doesn't have a clue when it comes to epoxy primer? :confused:

camaro41701
Nov 20th, 06, 08:51 PM
PPG told me I could use the epoxies over the sandblasted metal,but anything smoother did not have enough bite.Epoxies lay on top of the metal,Etching primers go down into the pores of the metal.Other brands may be different.I also asked about putting the epoxy over the etch.They said that was fine but seen no reason.I usually like to do my filler work over epoxy,so he said that would be fine as long as I let the etch flash the correct time.

tired68
Nov 20th, 06, 10:57 PM
PPG states "Chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system" That's a pretty clear advice. They also give alternate spec for sanding. All processes include washing and degreasing with wax and grease remover.

Their metal cleaner/conditioner is a phosphoric acid etch system that gives the metal tooth. You can prepare by sanding per specs. You can enhance adhesion by using their cleaning/etching of bare metal for superior results. Dupont and Sherwin Williams offer similar metal preparation products that work the same way.

You can spray an etch product and then spray epoxy. You cannot spray the etch over body filler though because it won't stick. Etch would help epoxy adhesion same as the metalprep steps. An epoxy sealer or other coating needs to be sprayed over the etch primer within 24 hours. That is the open coat window. Etch is not moisture proof, so it needs a barrier top coat applied within a reasonable time. If you miss the open coat time, you have to sand the etch before continuing. If your project sits a long time in moisture or gets wet while it's only primered with etch, it may be failing underneath because it's not water tight like epoxy. Etch is good product but it has a limited range of application for a weekend car restorer.

The product sheets are online. When you follow them, you will get good results.

http://www.ppg.com/refinishftpsite/docs/P-196_DPLF_Epoxy_Primer.pdf
http://www.ppg.com/refinishftpsite/docs/P-226_DX_Metal_Treatment.pdf

PPG epoxy stays "open coat" for seven days so it will form a chemical bond your next coat. While it's open it won't sand and you'll gum up your paper. It won't sand because the chemical reaction is still incomplete. It is designed to be gummy so the chemical is open to bond with another coat for the next seven days. That doesn't mean it's junk, it means you missused it.

If you miss the recoat window, you need to let it fully cure and then sand per the product instructions. Then you spray another epoxy coat followed by your topcoat. That topcoat must be sprayed within the new seven day open coat window. If you ignore this specification, you loose the chemical bond between coats. That can cause latent paint failure. It may look great and fail later on.

For sandable primers, spray on K36 or K38 high build products over epoxy which is in the recoat window.

http://www.ppg.com/refinishftpsite/docs/P-222_K38_High_Build_Primer_Surfacer.pdf

PPG, Dupont and Sherwin Williams have comparable product lines. All three make decent products.:thumbsup:

For my build

1) strip to bare metal
2) weld all holes
3) sand, strip, clean and then etch with DX520 and DX579 metalprep then wash/rinse and clean with acryliclean. Tack rag dust off.
4) primer with DPLF epoxy, your coice of color
5) sand off areas to do body work and complete all repairs
6) scuff the whole car per scratch desired per the product sheet.
7) epoxy with DPLF epoxy, 2 coats.
8) while epoxy is open, spray high build as needed, (K36 or K38) Add as many coats of high build as are needed to block the car to ones satisfaction.
9) block sand. Repeat step 8 where spots need attention.
10)spray sealer, such as epoxy mixed for sealing.
11)base/clear or single stage Follow the open coat window for base and clear.

go2fast
Nov 21st, 06, 08:36 AM
PPG NP270 is my epoxy of choice. Needs no etch, fights corrosion, highly sandable, and ISO free. Not cheap though.

sevt_chevelle
Nov 21st, 06, 04:46 PM
So, lets see. A company that specializes in coatings and chemicals having a market cap of 10-3/4 Billion dollars doesn't have a clue when it comes to epoxy primer? :confused:

Just because a company has 10 billion dollars in the market cap doesnt mean they know how to make a quality product for EACH product!
Each paint company has strong products and weak products.
Sherwin Williams has been known to make great primers, they are NOT known for making great topcoats.
GM for ex. known for making good trucks, personal and commerical grade, correct. But they cant make a car to save their arse.

Am fully aware of the chemical treatment with PPG epoxy so it meets PPG's max performance levels. But as I said eariler NOT all epoxies are the same! Many do NOT want etch under epoxy because the two will react and cause adhesion problems.

tired68
Nov 21st, 06, 10:36 PM
You have some interesting notions, but you have not cited a single example much less a trend of poor performance for PPG's DPLF when applied according to their product data sheet.