Chemical compatibility???

Simon Hitchen · #1 11-21-2007, 06:31 PM

Help is needed please guys.
Im using Rage extreme body filler and Rage metal glaze finishing puty to finish fiberglass pieces. Once sanded and as smooth as silk I use Dupont 2 Part epoxy S2505 primer to finish them off prior to painting. They all look great EXCEPT for the area covering the body filler.....
It looks as if the body filler is still gasing, lots of tiny pinholes, and general roughness. The filler generally lies for a couple of days between sanding and priming. Once ready to prime the whole piece is washed in soap and water then dried then wiped down with acetone then dried then primed. Im sure its some sort of reaction because the roughness is in the exact shape of the body filler. Once wet sanded down and repainted again its OK but this always adds yet another step and more primer, no fun.
Does anyone have any experience with this or ideas?? Im puzzled.
Thanx.

cytoxin · #2 11-21-2007, 07:41 PM

this is the nature of the beast. sand and prime with high build urethane primer is what i usually do at this point. good luck

Simon Hitchen · #3 11-22-2007, 12:50 PM

Just to clarify, the undersurface is perfectly smooth without pinholes or undulations. The very act of putting primer on the filler causes some sort of reaction to occurr. The finished product is really nice except for the area directly over the filler, this looks like it has the orange peel effect...

mike109g6 · #4 11-22-2007, 01:09 PM

Simon,
I use Rage also and have not had this problem, though I don't put epoxy primer over it. This leads me to think that epoxy primer is NOT compatible with Rage and I bet it is the the two different catalysts working against each other. There should be a compatibility sheet that came with the epoxy primer application directions; if not, a Dupont dealer should have the answer or you might try the Dupont website for compatibility issues. Urethane 2k primer(High build) is excellent and much easier to use than what you are using(probably costs a whole lot less also). Sands to a glass like finish with 400-600 wet/dry. Also you will find that you will not have compatibility issues if you color with urethane, or similar. If you decide on the urethane route just sand the epoxy primer off first before applying or you will end up with a real mess.
Mike H
PS - look on the Rage can to see what is NOT suggested to use over it.

szicree · #5 11-22-2007, 01:29 PM

I don't think it's a compatibility issue. When you sand filler, it will look and feel perfect, but it will almost certainly have some tiny pinholes that you can't see. They are full of filler dust so you can't feel them either. This is exactly what sanding primer (surfacer) is for. In fact, most folks don't really finish sand filler. You can sand the filler to about 120 grit, then surfacer, then sand with 400. Sanding filler to 400 grit is a waste of time, since it will always have holes and need surfacer.

MrNomad · #6 11-22-2007, 01:37 PM

Quote:

Originally Posted by mike109g6

Simon,
I use Rage also and have not had this problem, though I don't put epoxy primer over it. This leads me to think that epoxy primer is NOT compatible with Rage and I bet it is the the two different catalysts working against each other. There should be a compatibility sheet that came with the epoxy primer application directions; if not, a Dupont dealer should have the answer or you might try the Dupont website for compatibility issues. Urethane 2k primer(High build) is excellent and much easier to use than what you are using(probably costs a whole lot less also). Sands to a glass like finish with 400-600 wet/dry. Also you will find that you will not have compatibility issues if you color with urethane, or similar. If you decide on the urethane route just sand the epoxy primer off first before applying or you will end up with a real mess.
Mike H
PS - look on the Rage can to see what is NOT suggested to use over it.

I use RAGE too followed by Evercoat Metal Glaze, which is a polyester finishing and blending putty, and have not had this problem. I believe this is called a skim coat.

Next, I use a 2K primer & sand repeatedly till perfection is achieved, followed by a sealer coat, then topcoat. I never intermingle vendor products.

If you want to test if it's the primer, get some SEM shaker can and spray that on after Metal Glaze. If it dries smooth, you've identified the problem. My guess is with the previous post, the primer.

FYI: I could not find S2505 on the Dupont website.

Let us know what you discover.

Barry
Tucson

cytoxin · #7 11-22-2007, 08:15 PM

think of it as sanding a sponge..you cant get it slick, it just keeps opening up. the finer and finer levels of fill have smaller and smaller bubbles.

it will pull in some stuff and have a surface difference. it will at times look as though the primer has blushed on the surface that has the filler in it. what ever you do, if you get etching primer on the polyester (rage/bondo) make sure it is dried for at least 24 hours prior to topcoating it, or the acid will blister the topcaot for sure. ive top coated bondo (thats all it is) with alomost everything possisble. it always looks the same. it is especially bad if you use spray bomb primer due to the watery thin viscosity of the primer.
i always topcoat bondo with epoxy primer (nason ful poxy or PPG DP40)

NOTE ive always used the epoxy route because i was working with steel. it is water proof. primer surfacer is not. k2000 I dont know but it is very nice to work with. all will work, some work better. nothing sticks like epoxy's.

az_gila · #8 11-22-2007, 10:02 PM

Like Barry, I couldn't find the DuPont part number (S2505) you list...

However, this one comes close... if the "5" is an "S", and one digit missing

Epoxy Primer/Sealers

Epoxy primer/sealers are good corrosion-resistant products designed for direct-to-metal applications. They have a very sticky resin and will provide good adhesion to most substrates. Typically, they are not designed for filling surface imperfections or to be sanded (the sticky resin makes sanding difficult). They are ideal for use as a primer/sealer on bare metal that requires no surfacing. An example of an epoxy primer is DuPont's 2510S, 2540S and 2570S, which are two-component, non-isocyanate, non-sanding primers with corrosion resistance and excellent adhesion for direct-to-metal application.
These products are available in lead/chromate-free and chromate for use under body filler, polyester putties, primer surfacers and topcoats. These direct-to-metal epoxy primers can be applied over sanded or blasted steel, well-cleaned aluminum, and galvanized or stainless steel without sanding. They reduce the priming process to a few fast and simple steps: clean, apply one coat of primer/sealer followed by a 20-minute to 30-minute dry, then apply the topcoat.

If it's one of this family, then it is not designed to be sanded....

Can you clarify the part number?

gil A

cytoxin · #9 11-23-2007, 04:58 AM

Quote:

Originally Posted by az_gila

Epoxy primer/sealers are good corrosion-resistant products designed for direct-to-metal applications. They have a very sticky resin and will provide good adhesion to most substrates. Typically, they are not designed for filling surface imperfections or to be sanded (the sticky resin makes sanding difficult). They are ideal for use as a primer/sealer on bare metal that requires no surfacing. ?

gil A

thats how i use it. i use the filler (rage, evercoat, bondo, pirahna putty whatever) then epoxy prime, then k 36. you will never have to worry about the filler doing anything stupid, or the becoming penetrated by water ,redeucers only to give up the solvents later and cause the gloss to dissappear or surface to blister. YMMV. thats how ive been doing it for 20 years. still see some of my work from time to time and havent seen any of it look any different than the surrounding area.
the down side to epoxy primers for me is the topcoat time. usually 7 days or less. but you can strip a car, epoxy prime it, and leave it outside for months then get back to it at your leisure with no fear of finding rust or corrosion under the epoxy. YMMV

Simon Hitchen · #10 11-23-2007, 07:07 AM

Thanks for the help guys,

I was away from the shop when i originally posted. Now im back and with the can in front of me its DuPont 2540S LF Epoxy DTM primer/sealer Gray VS4. I consulted my paint shop guys before doing any priming, they said prime everything fiberglass to be painted eventually in this stuff once all surface imperfections are taken car of. It really does look excellent when done and if I do one light coat, let it dry, wet sand the affected area then recoat, the rage covers OK.
The paint shop guys said that when it comes to painting the aircraft in the next 18 months I would just need to wet sand the primer to remove any oxidation and then it would be ready to final paint.