So I'm getting ready to lay down a coat of DP50... In a prior post, I had asked about a very inexpensive (1K) lacquer primer that is on the fenders and doors. It was painfully obvious this needed to go away immediately... Now, once the lacquer primer is removed, will traces of it hurt the surface prep for the DP50? Should I go nuts getting rid of absolutely every last trace of this primer, or if there are a few thin spots of residue will it be okay?

In reading the Data Sheet, it appears that there may be lifting problems unless the DP50 is coated or has an additive in it, but what if the lacquer is only a few little opaque 1" spots? Same problem as if it had been left fully covered?

We'll be taking off the lacquer primer of course, but there's body work under it that I don't want to dig in to. If we can take off 99% and leave a few little remnants, I'd like to know it will be okay...

-c

I would remove as much lacquer as possible.
Also what hardner are you using with that DPLF epoxy? Ive been informed that they were having problems with the DP402 hardner.

Also if I remeber right is DPLF 50 white? if its white I wouold highly recommended you return it to the store and buy black or gray. White epoxy is very poor on adhesion and corrosion protection

It would be best to remove all the laquer primer, at least in the areas where it is over bare metal. The laquer primer on your filler areas will be more difficult to remove and it would probably be ok if just the majority is gone. I'd put two coats of epoxy down and move on to the primer surfacer if the bodywork is OK. You won't have any lifting problems. Bob

sevt; The DP50 is grey

I don't have the hardener with me, have to post back later, but the paint shop said they'd recommend the slower one as it gives a 72hr pot life, if that helps. What hardener problems have you heard?

Bob; I'm planning to get off as much of the lacquer as I can, but my initial concern was because I'm guessing the filler soaked up some and WILL be hard to get off. If I leave some on the filler, it sounds like it won't hurt anything, but we'll work to remove as much as possible...

The paint shop advised laying down a "fog" coat
to give the very light coat requirement. Two of these ultra thin coats you're thinking? The body work is good in these areas.

I'm also in the process of smoothing the firewall by straightening and filling the dimples, etc. Will use this same primer there too...

The slower hardner is DPLF401, you'll be ok.
Ive heard from a few PPG sources that the 402 is drying the epoxy too quickly thus having problems with adhesion and corrosion protection.

I personally have experienced the 402 peel on me a time or two. Switched to 401 stopped going it.

The thing I hate about the 401 is it requires an induction time of 30 mins. You MUST allow the product 30 mins induction before spraying. You mix it up then let it sit for 30 mins, then you spray it.

I would apply 1 light coat of epoxy, allow it 1 hr flash time then apply 1 more coat.

The DP40 is green, 90 is black, I also remember a red and white but can't remember the number :rolleyes: I've been using epx900, CRE-CT, and experimenting with a few other brands. I would remove enough of the primer from the filler areas to expose most of the surface area, a little bit on the primer here and there isn't really going to hurt anything I would think. Your right about the filler absorbing some of the primer but it shouldn't be a problem if you have some of the filler exposed for the epoxy to bite. I wouldn't fog the primer on, I wouldn't recomend dry spraying any primer. You need the primer to go on wet enough to obtain a good grip to the surface it is being applied. Get your gun dialed in so it lays a nice medium wet coat and allow the primer to flash good between coats,with epoxy you've got a very large window for recoat time so there's no problem with letting this stuff set for awhile between coats. The advise given to apply two ultra thin coats was probably given because epoxy does take a long time to fully cure and the thicker the primer the longer it takes. I like a good layer over my metal so two to three wet coats are usually applied. The parts are allowed to cure completely then I do my filler work and then recoat with epoxy followed by primer surfacer. Glad to hear you took the laquer primer off.

Laid down the DP50 late yesterday on the firewall - set down a thin wet coat after waiting the 30 minutes first. The recoat time is something like 1 week, so I'll put down a second one today.

We'll be smoothing the firewall, filling the dimples (WHY are those there?) with featherlite filler and then laying down the prime/sealer. How long should we wait to put filler over the DP50LF? The tech sheet recommends waiting overnight...

Also, should we sand/scotchbrite the DP50LF at all?

Definately wait overnight before you apply any filler. You will not need to scotchbrite or sand the primer if it is this fresh. If the primer gets older than a day or two I usually just scotchbrite the area before the filler is applied. The filler will adhere well to the epoxy. When your filler work is done, scotchbrite the entire panel and apply another coat of epoxy to cover any cut throughs and filler, then apply your primer surfacer.

Always good to review the product sheets which are available from the dealer or online.

http://www.ppg.com/cr-refinish/phase1/frmFindProduct.asp

From the caution notes, it appears that DP primers can be used over lacquer with some caution and in some cases a special additive.

DPLF Epoxy Primer comes in 6 colors;
DP40LF (Gray–Green), DP48LF (White),
DP50LF (Gray), DP60LF (Blue), DP74LF
(Red Oxide), and DP90LF (Black).

Thanks Ed; I did read the tech sheet and saw their recommendation for the additives. Seems like someone always has experience in doing things and occasionally has a better system than the obvious. I appreciate everyone's input, in any case.

We got the firewall stripped to bare metal and laid down the Dp50LF. Waited overnight and put down a coat of featherfill to cover the dimples and waves, etc. Sanded that down (and yes, have some cut-through's) and then added a feather layer to finish it. I'll add one more coat of epoxy before applying a final primer surfacer.

Thanks Bob, you're giving some good, EASY to follow advice. The paint supply shop we use has been good too - nice to have separate opinions that are the same! If this isn't a GREAT site!
graemlins/thumbsup.gif graemlins/thumbsup.gif graemlins/thumbsup.gif


-curt

One last question too...

WHY are those dimples and bumps in the firewall?
They don't seem to accomplish anything, yet it seems like every car has them...

Stumped!

That firewall is going to look awesome when you're done, and it should last a very long time the way you are doing it. The Feather fill primer is some really good stuff, I've been using the Feather Fill 2G for awhile with no complaints. I did a complete repaint on full size Chev pickup awhile back that a logger owns and it was showing alot of minor damage along both sides. This truck is abused in the woods every day. To save some time and also put the featherfill to the test on this budget job, I took 80grit on a DA and buzzed down both sides of the truck, then went over it quickly with 180 leaving all the minor dings, scrapes, etc. I put four coats of featherfill on the sides and let it sit for a day. Then guide coated the primer and went to town sanding first with 180, then 320, and finished with 400. All the damage blocked out just fine, the primer filled all the voids with no problem. I sealed my cut throughs and applied two coats of Elcheapo Omni black basecoat and followed that with MC260 clear. It actually looked really good considering how the job was done. I seen the truck today after 3 weeks have past and there is no die back, the gloss is good and I couldn't pick up on any shrinkage, but the temps have been -20 degrees at night here. I wouldn't suggest doing a quality job this way but it's nice to know what a product is capable of if pushed. I'll continue to monitor the truck for any problems, but I'm sure the owner will be pounding it to death in the woods. ramble, ramble, ramble. Anyways, I like the product so far. I've got a customer's $50K+ 69 Camaro in the garage right now that may see some Featherfill on it, I sure like the build for serious blocking. Bob

I looked at my car's firewall yesterday. I am in the process of putting it all back together and I also can see no apparent reason for the dimples. I looked on the backside(inside) of the firewall, but again, no apparent reason for them. Only thing I would guess is that it adds strength or rigidity? I wonder if they are always in the same place? Anyone know?

my guess is it has soemthing to do with either

A) Giving some surface irregularity to hold insulation pieces on the inside, or

B) A way of shrinking the over-all size during installation to "tighten" it.

It's an odd thing and I just don't see any real use for it unless

C) It's a by-product of the machine that stamps it...

Bob, I'm glad to hear of your ongoing experiences. The featherfill isn't the most expensive thing in the stable by any means, but so far, I've been real happy with it and it's workability. Haven't done a lot of real filling with it yet, but it was nice as a skim-coat on the fenders and doors. When the quarter skins get welded on here pretty soon, we'll be filling in the weld lines and we'll see how that goes.

Just finished re-coating after the final sanding on the firewall. DP50 doesn't fill sanding scratches completely, but there aren't too many and I'm betting the primer surfacer will complete the job. The firewall will ultimately match the yellow car body, so little imperfections in my amateur work will be difficult to see anyway.

THANK YOU for all your input!


-c