Think I would use POR 15 on that area, you can brush it on and will really stick to the rust much better than the DP will. You could always go over the POR with the DP but not really necessary.

 

My plan was to use naval jelly and 00 steel wool and remove the rust, and epoxy prime.

I did find some other threads about brushing epoxy primer and apparently the cure time is longer. It sounds like a foam roller might be the way to go.

I am in Minnesota and it is about 18 degrees today, but do have a heater in my garage. I am planning on doing this tomorrow. Was going to run to HF and pick up a 66222, but not sure I need it for this job, and I have a 25% off coupon for Thanksgiving day so I'll pick up the gun then.

So now my questions are:

How long between coats?
What temperature is best (surface and ambient)?

 

You could just spray some Rust Mort to neutralize rust and then follow up with epoxy over it. Everyone recommends SPI epoxy here, I'd give it a try.

 

I am no expert, but I have used PPG DPLF. I did take some classes at a local community college, in the winter, to get access to their paint booth.
The instructor generally recommended 55 degrees Fahrenheit minimum temperature, of the surface being sprayed.

If you cannot get your shop that warm, at least get some sort of radiant heat on the areas being sprayed, to get the surface temp up.

I am not familiar with the Harbor freight gun, but I use a 79 dollar HVLP gun I got at Home Depot.

I agree with your method of lots of elbow grease, steel wool, and Naval Jelly. I do not agree with the POR 15, or the Rust Mort some have suggested. If you can totally get rid of the rust, do that. If it is your own personal project, you want to do the best job you can do. You are not trying to beat a flat rate.

 

Most auto body materials need to be at 60 degress minimum to cure correctly..we use heat lamps for small areas in the shop..

Sam

 

Thanks for the replies.

I can easily get the garage up to 60 degrees, and will put some heat source on the floor boards, I do have an infrared temperature gun I can use to check temperature at the surface.

My tech sheet states 10-15 minutes between coats. Anyone know how long if rolled/brushed on? This is the best way for me to go, as ventilation will be hard to do with trying to keep the garage warm, and the time it will take to tape/mask off the interior for spraying.

 

In automotive it is called flash time and is a minimum under ideal conditions..your flashtime at 60 degrees and rolling will easily be twice that..so no hurries no worries..

sam

 

PPG DPLF is a poor epoxy primer. It has been discussed many times on this forum. There is no comparison whatsoever to SPI as far as price and durability.

DPLF will wipe right off with lacquer thinner and a rag once it has cured. You cannot do that with SPI....give it a try you will not be disappointed.

Vince

 

So 20-30 minutes between coats, that's not bad, thought it may take longer.

Is SPI sold at local auto body supply stores?

I am doing this today, garage heater is on and starting to remove rust, also got a cheap halogen light to help heat the surface up.

If I can not buy SPI locally then I am not using it.

 

Called SPI, local dealer is Parts City in Kimball, MN and is 95 miles away and delivers into the metro area, however is out of town at a funeral until next week according to voice mail, must be a one man show.

 

Just because a primer can be wiped off with lacquer thinner is not a good test of the quality of a primer. I am no chemist, but after a primer is applied, and cured, I would think a softening, or even a partial dissolving of the top layer of the primer, by a strong solvent, that is not even commonly used anymore, would only increase the adhesion of the top coat put over it.

One of the best resources of information is your local paint store. They know the products they sell, and are very familiar with them.

 

While looking for my DA sander I found some old PPG DP50LF which is the same I just purchased only in a gray color.

By old I mean I have had this for 12 years! Is it worth using? Still shakes and moves in the can, and it was opened at one point. Also have the DP402LF catalyst along with it.

 

I am no expert, but I have used PPG DPLF. I did take some classes at a local community college, in the winter, to get access to their paint booth.
The instructor generally recommended 55 degrees Fahrenheit minimum temperature, of the surface being sprayed.

If you cannot get your shop that warm, at least get some sort of radiant heat on the areas being sprayed, to get the surface temp up.

I am not familiar with the Harbor freight gun, but I use a 79 dollar HVLP gun I got at Home Depot.

I agree with your method of lots of elbow grease, steel wool, and Naval Jelly. I do not agree with the POR 15, or the Rust Mort some have suggested. If you can totally get rid of the rust, do that. If it is your own personal project, you want to do the best job you can do. You are not trying to beat a flat rate.

You don't want to spray epoxy over rust or where rust may still exist. That's why you'd put down some phosphoric acid (Rust mort, por15, etc) first and then go on with epoxy. However its your car and you can do it way you want to do it.

 

In post 3, T4Turtle said he was going to remove the rust with Naval jelly, and 00 steel wool.

I went and got my data sheet for DPLF. here is what it says about surface prep:
1. Wash with soap, and water, then clean with DX 330
2. Sand bare metal completely with 80 to 180.
3. Re-clean with DX 330, wipe with a clean damp cloth, to remove cleaner residue.
4. Chemical treatment, or the use of a conversion coating will enhance the adhesion and performance of the finished system.
5. Prime carbon steel immediately after cleaning.

Naval jelly is phosophoric acid, in a gel. i am not a fan of POR15, or Rust mort. I know it is a PITA, but remove the rust with the steel wool, and naval jelly. Using the naval jelly is using a conversion coating.

As far as the old DPLF, open the can, and look at it. you also have a new can you can compare it to. The old can probably has some solids settled into the bottom. break then up, with a stir stick as best you can. Then shake, stir, or use a mechanical mixer on an air drill to mix it throughly. Maybe take the old can of DPLF down to the paint store, and have them put it on their shaker. Again compare it to the new stuff.
To be safe, mix up a little of the old stuff, and spray a test panel.

I used this basic process on a boat trailer. Unfortunately, I just did it this summer, I will have to get back you in five or so years, let you all know if the rust has reappeared. There were several places on the boat trailer where I would sand, scrub with steel wool, and Naval jelly, use a wire wheel on, re-sand, re-scrub with steel wool, and Naval jelly, back to the wire wheel, and with each cycle, more rust was coming off the boat trailer.

I would use the old DPLF, but I know the conventional wisdom is to not use it. That is why I suggested to do a test panel.

 

I am not spraying over rust, I am removing rust with naval jelly and steel wool, same as phosphoric acid....

I did find a couple pin holes while removing paint and prepping surface.

Should I use a body filler or fiberglass mesh along with the epoxy primer?

 

Thanks DanielC, I'll check it out, and see if it looks similar. Be nice to use it, but don't want to make a mess of things and cause more work.

 

Just because a primer can be wiped off with lacquer thinner is not a good test of the quality of a primer..

It most certainly is if the primer is marketed as an epoxy primer. I have experince with PPG DPLF and also with SPI. SPI is hands down a more durable primer. Just do a search in this forum for PDLF primer and see what you find.

One of the best resources of information is your local paint store.

Not true most of the time. Nine times out of ten the guy or gal behind the counter knows next to nothing about their products or pushes what the collision shops use because that is what they sell the most of.

Vince

 

So, can finish my prep work today and wait until next week to prime with the SPI?

 

Vince,
Might I suggest you find a better paint store. I must be lucky. I actually have three paint stores, that I would trust the advise from. Not believe without questioning, but I would certainly take the advise they give me. The one I use most often, was in business in the 1970's, and is still in business. If they gave bad advise, they would have gone out of business long ago.

As far as a primers ability to resist strong solvents, again I will say, that is not what a primer is for. Primers are intended to be top-coated, and the top coat gives the chemical resistance.

Regarding the SPI epoxy, I have never used it. I am unfamiliar with it. It might be great stuff, I do not know.

However, if you go back to the beginning of this thread, you will notice T4turtle asked about PPG DPLF.


Addition after last post
T4 turtle
If it was me, I would prime with DPLF. You have it on hand. Do not wait for next week. the metal will surface rust again.
Prime immediately after cleaning.

 

Vince, Regarding the SPI epoxy, I have never used it. I am unfamiliar with it. It might be great stuff, I do not know.

I suggest you try it, I can assure you that you will never go back to the high priced spread.

Vince

 

SPI is well priced imo and if I had to buy epoxy right now I'd definitely go get some. DPLF is high priced primer but so is most of PPG paint line except Omni

 

Now that I think about the DPLF I already have it may have only be 8-10 years old as it is gray and I did a silver Supra around then. When did it first come out as the lead free version?

 

Now that I think about the DPLF I already have it may have only be 8-10 years old as it is gray and I did a silver Supra around then. When did it first come out as the lead free version?

Perfect time for you to get your hands on some SPI epoxy primer. You can have a two gallon kit for what you would pay for a quart of DPLF and catalyst.

Vince