Simon Hitchen

Simon Hitchen

Well Known Member
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.
 
IMHO

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
 
Clarification

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...
 
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 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.
 
I use a 2K primer & sand repeatedly till perfection is achieved

mike109g6 said:
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.
Click to expand...

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
 
it doesnt matter how slick you sand it

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.
 
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Part numbers...

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....:eek:

Can you clarify the part number?

gil A
 
thats how i use it

az_gila said:
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
Click to expand...
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
 
Correctioin

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.
 
Here lately I've been shooting fiberglass parts with gray PPG DPLF epoxy primer as a pinhole and surface check. You can't see what you really have until you shoot the first solid coat of something. If it looks great, you can shoot an immediate coat of K36 per the so-called "wet-on-wet" method recommended by my PPG rep (and DuPont as noted by Gil).

If it needs more work, no problem. True, it is a little gummy to dry sand, but it wet sands just fine. The big plus is that you don't have to sand off every speck of it before overcoating or making a surface correction. It should be fine under almost anything, unlike some other primer choices.

Missing the 7 day window is moot if you don't mind a little wet-sanding. I'm storing most of my glass parts in epoxy primer. The plan is to get all the "dirty" glass work done now (layups, filling, shaping, sanding), then later wet sand, reprime, and spray any K36 and the color coats when I have the shop cleaned up and in the painting mode.

As for Simon's problem, I'd suggest that too much or too little catalyst may be the problem. I did some reading at the Evercoat website a few years back and recall a note to that effect. Unlike epoxy, there is nothing exact about the mixing method. Unreacted component (base or catalyst) is free to react with other stuff.
 
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Simon Hitchen said:
Thanks for the help guys,

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.
Click to expand...

This is totally incorrect. Though it is a mistake that is made often because RV builders don't understand all of the properties of paint.

Epoxy primer (when being used as a base coat for finish paint) must be re coated within a max amount of time (commonly 48 hours). This is always specified in the product data sheet.
If this is not done, the solvents in the paint will not be able to soften the primer to provide a mechanical bond between the two because the catalyst will have fully cured. Being catalyzed is what makes epoxy paints so durable and unaffected by solvents (even the solvents within paint you are applying to them.

The purpose of most primers in paint systems is that they adhere very well to most any surface. The paint is then applied to the primer (within the specified amount of time) and with the chemical bond it develops with the primer, you now have a durable paint finish that is well adhered to all of the different material surfaces of your airplane.

Any primer (particularly catalyzed epoxies) that have been in place for an extended period of time should be surface sanded and then re topcoated with at least a light coat of primer specified for the paint being used.
 
DP50LF color Q.

Dan, or anyone, what is the color of DP50LF?

The spec. sheet calls it "gray", but is it a light gray or a dark gray?

Anyone know?

...thanks ....gil A
 
OK...

brenegan said:
It's a light gray, here's a pic for the color...
Click to expand...

Thanks David... I was hoping for a dark gray for the nether regions of the cockpit...

The DP 40 LF is a bit too "greeney" in it's dark grey to leave exposed....

thanks gil A
 
Scott is completely correct. I mentioned storing my parts with an epoxy primer coat already applied, but they will indeed need sanding and then a fresh, uncured primer coat just prior to sealer and/or topcoats. Poor writing on my part; I'll edit the previous post.
 
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az_gila said:
Thanks David... I was hoping for a dark gray for the nether regions of the cockpit...

The DP 40 LF is a bit too "greeney" in it's dark grey to leave exposed....
Click to expand...

Although it's a light grey; when comparing even lighter shades such as what I have here for the bulkhead & lower fuse, then it appears quite a bit darker. The DP50 is surrounding the corrugated bulkhead panels of the baggage compartment.


(note: if it looks as though there is a bit of blue tint, there isn't. It's just the photo)

L.Adamson

http://img139.imageshack.us/img139/6855/dsc05228reducedic9.jpg
 
Thanks...

L.Adamson said:
Although it's a light grey; when comparing even lighter shades such as what I have here for the bulkhead & lower fuse, then it appears quite a bit darker. The DP50 is surrounding the corrugated bulkhead panels of the baggage compartment.


(note: if it looks as though there is a bit of blue tint, there isn't. It's just the photo)

L.Adamson

http://img139.imageshack.us/img139/6855/dsc05228reducedic9.jpg
Click to expand...

Thanks L...... perhaps I would call it medium gray.. but I have male color sense, so what the heck...:)

It seems I could do what you did, since my selected interior color is a pretty light grey (1994 Astro Van interior). I want to cover up the Akzo green primer, and then use the correct interior color in the visible parts that wont be covered by upholstery.

Since the Akzo is so old, my thought is that a primer will stick to it better than shooting a color coat directly. Of course, it will be MEK cleaned and 100% scotchbrite rubbed...

The effect in you cockpit is nice... I presume that the DP50 holds up well since it is an epoxy?

thanks gil A
 
az_gila said:
The effect in you cockpit is nice... I presume that the DP50 holds up well since it is an epoxy?
Click to expand...

That DP50 has been there for around eight years, and does hold up well. My plane was a "slow" build. I started with the DP 40 (green) for the wings.

I just re-painted the bulkhead & seats last month, since I had a gallon left, from the aircraft exterior. Figured that I'd put some light gray fabric over the DP50 primer; but now, I might not, as they have a rather good contrast together.

L.Admason
 
Solution

Thanx Guys,

Had a good read and did some more research and some experimenting.

Turns out that when I mix in more catalyst to the filler it obviously dries faster but also eliminates the problems I was having with the primer over it. Guess that I wasnt using enough catalyst and the filler was still gassing a little.

Thanx again.
 
DTM primer

I painted my RV-6 with the 2540S DTM primer in VS4. There was several areas where I had used bondo on the cowling and it wrinkled the primers when it was top coated. Mostly right around the edges. I sanded out and hand painted on some layers of a 2K high build primer around the edges to cover. Then I resanded (careful not to break through) and reprimed with the DTM. If you get in a real pinch and don't want to totally sand off the product and start over you can get a special water borne primer ( non-reactive) to seal it off then reprimer and top coat. This is a last resort measure to save you hours of extensive sanding but it's not cheap. If you really need to know the product name I could find it somewhere amoung my paint stuff.
 
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