Primer query Ditzler DP40

[swood1]

Hi all,

Just querying the primer paint system of choice now when restoring these cars.

I can see a number of people are using Ditzler DP40 as it's a good match to the original colour undercoat but I notice this paint system is 2k.  Is this now the direction of choice for primers?  Wouldn't the original paint system have been cellulose?


Steven 

[George Des]

DP40 is PPG’s epoxy primer. It is two part, but not in the same sense as the two part polyurethane top coats and primer-surfacers in that it does not use a polyisocyanate catalyst which is fairly toxic to spray without proper respiratory protection-a supplied air one is highly recommended. This is not to say you can spray DP40 with a any respirator at all. The epoxy primers such as the DP line are pretty much the gold standard for corrosion protection

[wwheeler]

I have sprayed DP40 and the black color DP90 quite frequently. While I am no expert on its chemistry, its smell is very strong and a quality respirator is a must! While you can blend these to get just the right color, DP 40 alone is pretty darn close to what Mercedes used at the factory. A great product.

Attached is a picture of a '70 Roadrunner I just finished that has the base color blend of 40 and 90. It also has the correct body color overspray of purple. The other "secret" is to use a satin/semi-gloss clear to seal the underside. That makes cleaning very easy. I use PPG D8117 and D8115 pre-flattened clears. These are the same clears that they use on the dull finishes on AMG cars and such. Again, you can blend these to get the correct gloss level and in this case, make it look as if nothing is on there.

[swood1]

Interesting comments.

Do you seal the DP40 on the underside of the vehicle only?  If you seal the whole underside don't you still have to add stonechip to some areas? 

I assume people use the same DP40 primer on the body panels themselves with a high build primer on top..


Steve

[wwheeler]

The PPG line of epoxy primers (DP 40 is one color) is meant for the whole car. So for instance, you would bring the body down to bare metal, spray DP 40 everywhere. Then do the body work on the topside (body filler and high build primer) on top of that. Then spray the DP40 over that to seal it in. The body color (and clear if used) goes on top the last coat of DP40.

Same process underneath, but normally you would skip the body work. The reason I use clear underneath is to seal the epoxy primer. It will stain if grease or oil gets on it. The clear makes it easy to clean.

[swood1]

Wallace thanks for this. 

I know about cellulose but I need to read up on applying Epoxies to car bodies as I have little knowledge on these.  If I can apply epoxy at least I can protect the body better as I progress with things.  Out of interest can Epoxies be brush applied say on inner box sections? 





Steve

[wwheeler]

It can be brushed on! Don't tell anybody, but I did that on some spots on the body so just so I could prevent rust from forming. It is a little thin, but is manageable. When I went to topcoat with primer filler, I sanded the DP40 to smooth the rough brushed surface. It does not sand very well dry and is best to wet sand.

You can also use a small roller brush to apply it in spots. Yes, I have done that as well. SHHHHHH. It is just a whole lot easier than getting the spray gun out and going through that.

[George Des]

DP40 is one in a line of PPGs epoxy primers. As pointed out DP90 is the same product only black in color. It is a great primer and is applied to the bare metal after the metal is treated with PPGs line of phosphate washes. The epoxy primer is so strong that it is designed to have any body filler applied over it rather than under. I used this when i did a bare metal spray on my 230Sl. To smooth out any imperfections I used PPG 2K primer surfacer K36 which is an acrylic urethane product that does contain the polyisocyanate catalyst. K36 is built up in several layers and can be sanded to a beautiful base over which any of a number of topcoats can be applied including single stage or base/clear coats. The key to any of these spray jobs is to stick with one manufacturer’s line of products to ensure you do not run into any compatibility issues. PPG, formerly Ditzler, has a full line of produces from lacquers to acrylic enamels to polyurthethanes. Their data will  sheets will indicate which of their products are compatible with their other products. Other manufacturers such as Glasruit carry similar lines.

[wwheeler]

What I have heard concerning why you put the body filler between layers of DP 40, is moisture control. Body filler will absorb moisture over time and of course swell. Since the epoxy primer is a seal coat, it encases the filler and prevents moisture from getting to the filler. Another really good primer filler is PPG NCP 271. It sprays on a heavy coat for filling and sands so well you cannot believe it. Great for block sanding. It can also be used as a seal coat with addition of a reducer.

Btw, the correct part number for the DP line has a LF after the number. So it would be DP40LF and uses a catalyst which is usually DP402LF. 

[George Des]

Yeah, the DPXXLF replaces the DPXX. The products with the LF suffix are lead free. I have used both and they work equally well. The product you mention with NCP is also a good product and as a bonus does not contain the polyisocyanates in the new cure process (ncp) catalyst.

[wwheeler]

Interesting. I would imagine the non-LF version is probably long gone. I started using NCP probably about 15 years ago and may have been new at that time. I had no idea that is what NCP stood for. It is fun block sanding NCP except for the fact when you see the dust on the floor. Sort of like dollar bills laying on the ground. Like all automotive paint, that stuff ain't cheap. 

Thanks.

[George Des]

Can’t recall how long ago the lead containing product was done away with-may be last 15 years or so. Some may still be hanging around but my guess difficult to find bu the new LF is just as good. The product to catalyst ratio is different. So the cost works out to be a little higher for the same amount of ready to spray product. Yes, these modern paints systemsbare not cheap compared to the old days of lacquers and synthetic enamels. They do require special respiratory protection if they contain any polyisocyanates but they are relatively easy to spray, dry quickly, can be color sanded and repaired easily, and provide a very deep shine and durable finish. PPG,  Glasurit, DuPont and R&M all have their own proponents and similar lines of products. I chose PPG primarily because it was readily available to me locally.

[swood1]

Hi all,

Thanks for your feedback on this, I was just wondering do the steps below all make sense when painting BIW:-

1. As repairs are progressed apply DP40 by brush to any areas that will be closed up (eg.  Footwell panels, sills and floor box sections).  I don't really want to set my gun up for small box sections if I don't need to.
2. Remove all old paint and take out as many dents as possible from original body.
3. Once body is complete/rustfree spray with two coats of DP40.  (Protection for steel).
4. Fill any dents as required and add seam sealer to all metal edges/gaps.
5. Once filling is complete spray again with two coats of DP40.  Wet sand.
6. Spray with PPG NCP 271 high build primer, wet/block sand back.
7. Apply stonechip to underside.
8. Body now ready for paint shop. Spray desired finish colour.
9. Clear coat applied to whole body (top and underneath).[/li]

Regards

Steven

[wwheeler]

1) If you do not see it, brushing is fine but I would do two coats to makes sure you cover all of the brush marks.
4) Yes, seam sealer over the DP.
5) Don't wet sand the DP. It is a seal coat. What you do to top coat the DP is to "scuff" the surface with Scothbright. No need to use abrasive paper. NOTE: NCP is a sealer as well and can be used instead of the DP. Google the data sheets for both these and you will see what I mean. That way you avoid spraying yet another coat of DP. Also, if possible, use different colors of DP and will be a "red flag" when you are about to sand through a coat. You NEVER want to go through the bottom seal coat. So make sure you know what color that was.   
9) You will want to use a flattened clear coat for the bottom if you want that. My guess is around a 30% gloss? http://us.ppgrefinish.com/PPG-Refinish/Training/Tech-Info/Articles-How-Tos/Low-Gloss-Finishes  This article will help. You can blend the two to get what you want. In days past, I had to add flattener to the clear which was never consistent. This new clear product is a dream!

I actually think it was more like 40% to match the gloss of the DP40.

[swood1]

Hi Wallace,

Thanks for this.  I now need to do some research and find a supplier.


Steve

[George Des]

Before you apply the DP epoxy to bare metal, you really should consider “washing” it down with the PPG metal prep. Can not recall the number but there are two or three different products and one is specifically for the aluminum panels. It basically addresses any microscopic rust and oxidation that remains on the metal. Also, be aware that DP epoxy primer has an “open” time where it must be overcoated after a certain period of time-I believe 24-72 hours or it will need to be scuffed and recoated with DP before applying any topcoat or primer surfacer. This is to ensure a maximum chemical bond between coats.