Body filler question.

Barry

Paint Fanatic
Staff member
I had a very high end restorer call me last night who has been a customer for about 18 years, and I was shocked with his question.

He asked what I knew about the 3m body filler bubbling 3 to six months after the car was painted?
I had not heard, but he was redoing one now. He personally knew two other restorers, one very high-end that was an SPI customer but did not say who was redoing two jobs now bubbling off epoxy and another where it was bubbling off bare metal.
This is the filler AKA Marson, Dynatron I have recommended for quality and price.
The answer that struck me funny is 3m told the one shop with two cars to send a bill??

Does anyone know what's going on here???
This is all new to me.
 

BoostedOne

New Member
Thanks for the heads up.
Glad I only used it once, about 6 years ago when the local PPG jobber was giving away free clean sheets with it.. I used it for two applications and didn't care for it. Sticking with Rage Gold.. I may not use the greatest new thing out there but stuff like this is why I am reluctant to change.
 

elwood

Promoted Users
Thanks for the heads up.
Glad I only used it once, about 6 years ago when the local PPG jobber was giving away free clean sheets with it.. I used it for two applications and didn't care for it. Sticking with Rage Gold.. I may not use the greatest new thing out there but stuff like this is why I am reluctant to change.


If it works no need to change.
 

Chris_Hamilton

Trying to be the best me, I can be
USC had a very similar problem some years ago with their Basecoat/Clearcoat Extra filler. Cars would bubble 3-6 months down the road.
 
I have been using the regular Marson Platinum for years now (even before 3M bought them out) and have never had any issues.
Tried the "plus" once but didn't care for it and have seen no need to change fillers. Makes me wonder if it is something in his process that is causing the problems?
The other option is that 3M knew they had a bad batch out there and hence the offer to pay the bill.
 

old soul

Member
If they have a known bad batch it would be nice to have a date code or batch number to check.
I just looked at my can of Platinum and could not find any identification numbers so that might not be possible.
 

Barry

Paint Fanatic
Staff member
My guess is if there were a problem it been corrected some time ago, it would be nice to know for sure.
Until then, I will not recommend any filler as a common call but none of my business.
 

chevman

Oldtimer
Here is a write up I saw about 10 or so years ago, so some of it may be outdated??? It was written by someone called "Overspray" on some other forum. The bubbling does sound like a moisture problem to me, and a lot of guys lay this stuff on too thick, it leads me to think its operator error, and not a 3m problem. "Overspray" also addresses pin holes, here is what he had to say about fillers.

"I use to work as a technical/sales rep for the company that makes rage filler. I know the guys (chemists) that developed the resin for rage filler. I've been a bodyman/painter,sales rep and technical rep for 30 years. The resin in rage and other body fillers is fiberglass (polyester) resin. Today's resin technology makes the adhesion of these new resins as good or better than most epoxy adhesives (glue). They are designed to really stick! Most critical is to be clean and moisture free.

Body filler resin is a thermal set plastic-it cures with heat. The hardner-MEK peroxide is a catalyst that produces heat in the resin. It needs to be at 64 degrees F minimum, to cure-best is 72-80 degreesF. If the metal is cold the filler will cure from the outside in and could trap some moisture and solvent from the resin underneath-causing adhesion or bubbling problems later. (Styrene is the solvent in resin and produces the smell/odor we associate with bondo and fillers). Also moisture (humidity in the air) will condense on the surface of the cold metal. This is the same effect you get when the mirror in the bathroom fogs up when you shower. The mirror and the metal of the car are about 10-15 degrees cooler than the air temperature and the humidity condenses on them. If you warm the mirror or the car metal to about the air temperature, the moisture won't condense on the surface. Using a heat source to warm the panel will eliminate the moisture being trapped under the filler (which can show up as rust under the filler) and help keep the cure temperature even through the filler, just don't overheat it. This is the way the chemists designed the product to work.

You can use extra catalyst to speed the cure, but too much will cause too much heat in the reaction and crystalize the resin which causes it to be brittle and break down (yup-more problems later). If you head to the autobody supply store for more hardner you may be using too much and looking at problems down the road. PreWARMING the metal and keepin the shop warm will let it cure more evenly with the correct amount of hardner. Heat lamps or lights should be far enough away so the panel feels warm when you put your bare hand on it (NOT HOT).

The correct amount of hardener is 1 1/2 to 3%. Here's an easy way to figure it. On the pallet or board you mix your bondo or filler on, put the amount you are going to mix up in the form of a circle. With your spreader or mixer divide the circle in half-50%. Divide the half in half-25%-half again-12.5%-half again-6.25% half again-3.125% (this is the maximum) half again-1.5% (this is the minimum). If you have a COLD shop put a small batch on a WARMED test panel to check the cure time-spread to about 1/4 inch thick. It should be fully cured in about 30 minutes to 1 hour depending on the temperature and hardner amount. (Yup, I know you can add a pile of hardner and get it to "kick" in a few minutes), but a good cure time lets the gasses come out and gives ample time to work out the air pockets with the spreader. (eliminate "pinholes") After a few times you'll be able to gauge the amount of hardner for the size of the filler batch you are mixing. There is some room here for a little extra-but not a lot of extra hardner. REMEMBER, this needs to work with the temperature of the air and metal.

Filler also contains talc (the mineral in talcum powder) which will absorb moisture. If you try to fill holes in a body panel, moisture can be absorbed from the back side and cause the area to swell and bubble. Also bare filler left in the weather (rain) for any length of time can absorb moisture and cause problems later. It will cost a lot less to follow these steps of correctly preparing the metal and working with the correct temperature range and hardner amounts than to even bother with epoxy primer as an underlayer. Between coats of filler DO NOT wipe with solvent (thinner).(Solvent will absorb into the filler). Rough up the areas not sanded and blow the dust off real good then apply a new layer. Thickness of the layers should not be more than 1/4-3/8 inch. If you put filler on too thick the heat in the reaction will be concentrated and higher in the thick area and could lead to crystalizing the resin in that spot making it brittle and subject to cracking later. Also too thick can mean you won't be able to get all the air pockets smoothed out."
 

Barry

Paint Fanatic
Staff member
Great post, Chev!!
It's sad filler, and paint companies dont make it public more often.
I take a beating for my warning on temperatures with epoxy,
I had a ppg shop tell me a few months ago I need to fix my epoxy as im the only company that has these restrictions.
I would have explained if asked, but he was a jerk, so all I said was there are a lot of epoxies for you to choose from.
 

shine

Member
in the old days we would put a heat lamp on the metal in the winter . i did the same with fiberglass when doing vettes . heat the glass or metal before you start .
 

Lizer

Mad Scientist
That is scary. I wonder if some genius changed the filler recipe to overcome a pandemic materials shortage and keep production moving.

Don
Would not be surprised at all. I develop diagnostic tests for animals for a living, and one of the materials we get from our suppliers straight up doesn't work anymore. Makes the project have really bad results. They say no changes in critical reagents but if their supplier had a change then that can make all the difference.
 

Barry

Paint Fanatic
Staff member
Would not be surprised at all. I develop diagnostic tests for animals for a living, and one of the materials we get from our suppliers straight up doesn't work anymore. Makes the project have really bad results. They say no changes in critical reagents but if their supplier had a change then that can make all the difference.
That is fing truth!!
I've never seen anything like this in my short 45 years.
 
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