How long to wait, or to let bondo "breathe" before applying my primer? It dried over night and I sanded it a bunch, it hasnt had any applied since yesterday, just sanding. Can I apply primer and be ok? Bondo scares me sometimes.... :D

overnite is overkill i usual wait a few minites you can tell when it cools down and its rock hard.

Uhh... I would wait at least a day, myself just to be on the safe side...

If you waited a day body shops across the WORLD would be backed up and get NOTHING DONE.

By the time its hard enough to sand and by the time you get done sanding it its time to prime it. Waiting a day waiting a hour is OVERKILL...Eric

I've been waiting an hour or so, then sanding then spraying primer....... worked fine so far graemlins/thumbsup.gif

i hate bondo!! there is a new aluminum type filler that is much better !! lil harder to sand but last longer and dosnt rot metal like bondo!! ill find out the name and post it later!!

bondo doesnt rot metal rust destroys the metal. it doesnt matter what you put on there you got to get rid of the rust. i seen bondo last a long long time so its not the bondo ..

There are so many "old husbands tales" about polyester body filler (aka "Bondo"). If it is used properly the repair will outlast all of us. We will be dead and gone and that filler will be there on the car WITHOUT any rusting of the metal, falling off or any of the other "tales".

As far as waiting before primer, everyone is right in that if it is hard enough to sand and feather out, it is hard enough to prime.

But just to add a thought, it is not "FULLY" cured for 12 hours, or so says some tech sheets. So, if you were to wait twelve hours after sanding before SEALING it under primer, it sure as heck isn't going to hurt anything.

If it were to be FULLY cured and the primer applied properly atomized and allow to flash off well between coats, it is bound to eliminate some shrinking that you "can" get when you push it.

I have to repeat what others said, it is largely an overkill. But just so you fully understand.......

Thanks guys. I just heard that it needed proper time to breathe which makes some sence. I've primed and painted stuff over after it got hard, 30 minutes at the least on past rides, the chevelle has some cracked bondo on the rear quarter, nasty little area. It has rust under where I pulled off the bondo piece. On the metal that is... So maybe the metal wasnt properly treated before someone glopped on the filler....

I dont think i made my self clear enough there are alot of idiots around illinois that try and make rear qrters out of bondo to save some cash !! and if bondo is used to fill a (hole) it will trap moisture and cause further damage, not to mention around here (illinois) during season changes the bondo jobs usually bubble and or crack!! it was ment as a small scratch or ding fixer in a thin layer not to patch holes!! thats just my opinion anyway use metal to repair rust!! graemlins/hurray.gif

Originally posted by pnutkemist:
the chevelle has some cracked bondo on the rear quarter, nasty little area. It has rust under where I pulled off the bondo piece. On the metal that is... So maybe the metal wasnt properly treated before someone glopped on the filler.... Think about that, the "bondo" was cracked that allowed the moisture to get under it. Why it cracked, who knows. It may have been too thick, then it was stuck by something from the inside to bend the metal out, cracking the filler. This is common on quarters near the trunk (at least the outward dents that is).

I had TWO and a half GALLONS of filler on the roof of my truck from my poor work chopping the top when I was 16 years old. It was 1.5 inches thick! It had hair line cracks but never fell off or anything like that for 20 years after it was done!!! That is an extreme example of how NOT to do it and it still hung in there. http://members.aol.com/buickfam/mytruck.jpg

as I stated before martin sr here in ILINOIS not sunny califonia , it gets severly cold and hot which tends to crack or pop the bondo out without being struck by something !! id use the hell out of it if i lived in cali.!!! graemlins/clonk.gif

I've been slinging bondo for a couple of days now on my project. I sand mine once the heat is gone, It takes about 20 minutes.

Originally posted by tony r:
as I stated before martin sr here in ILINOIS not sunny califonia , it gets severly cold and hot which tends to crack or pop the bondo out without being struck by something !! id use the hell out of it if i lived in cali.!!! graemlins/clonk.gif Tony, I am not kidding, "If applied properly" I don't care where you live, it will out last you and I.

I live in Nebraska (is that close enought to Illinios weather for you) and hever never seen bondo that was properly applied crack, peel, bubble, cause rust or any other problem. Good old polyester filler in my mind is still the best material for the job. The stuff is cheap, easy to work with and will last the life fo the car. I look at it this way, the roof seams on my Chevelle were done in Jan of 1970. That means that those seams lasted through 28 Nebraska winters and I still had to grind out the stuff when it came time to remove my rear quarters.

THATS ALOT OF ROOF FILLER! I preffer not to use any, it was my intensions on this project. But even on newer panels and areas that it couldnt hurt, Ive used some. And this rear quarter could have been worse. Im going to sand it off and clean the metal and apply it properly. I cant beleive there was that much on your roof. Thats just an insane ammount of filler!

Originally posted by tony r:
here in ILINOIS not sunny califonia , it gets severly cold and hot which tends to crack or pop the bondo out without being struck by something !! id use the hell out of it if i lived in cali.!!! graemlins/clonk.gif I live in nortern Iowa is that close enough to the friggid temps you experience in ILL?? smile.gif

Sorry but but Ive yet to see filler just POP out for no reason. What do the guys in MINN and WIS do then or even our friendly neighbors WAY UP NORTH use :confused:

What about the people in south Texas or Flordia, am guessing it gets a tad hotter down there then ILL.

Surely they still dont use lead or have some secret little weapon stashed in the back

Originally posted by ELLI:
I look at it this way, the roof seams on my Chevelle were done in Jan of 1970. That means that those seams lasted through 28 Nebraska winters and I still had to grind out the stuff when it came time to remove my rear quarters. The factory used lead, if it had plastic filler someone has been in there before you.
Ron

ok im not saying bondo is t terrible thing but are u guys serious u have never seen paint crack that was put on a thick hunk of bondo?? or the bondo heave from cold weather to hot?? im not talkin about the 1/32 thick filler jobs but the globbed on ones like guys that try and make new rear qrters out of mud!!! im not talkin show cars here but the ones u see at walmart that look like u could surf on or for example look at the post i made lookin for an l-88 style hood (bowtieaaron) posted a reply with pics that show exactly what im talkin about a steel hood with fiberglass scoop on it mounted with rivetes and mud u can see the cracks!!! if u have never seen this apparently u havent looked at many cars!!! :eek:

another thing i have seen through the years is the big bubbles from the mud buldging under paint none of u have ever seen this???? i can`t tell u how many cars like that i saw in Iowa when i was lookin for my chevelle supposedly (rustfree) big thick globs of mud buldging out from in front of rear tire where they filled rust holes the size of your fist with bondo!! if u guys dont think this happens your livin in a dream world!! why do u think the true (rustfree) cars are brining so much$$$$$$$must be cause there is better paint colors to choose from when u dont have to worry about (hiding ) the bondo like u dont realy ever see a gloss black car full of mud?????? cuase it shows the buldges that i was talkin about!!! graemlins/sad.gif

Same as with paint: It's only as good as what it's on. Prepwork, Prepwork, Prepwork!

I've got exactly the type of "Bondo-Pop" you describe on the driver's quarter of my '64.
Know why? I stuck a screwdriver in the crack and pried off what I could. There was a pinhole of rust and a line of rust extending fore and aft from the pinhole. I can only guess this was a repair from a "bouncing scratch" or something like a runaway shopping cart hit in the car's past. The filler that's 1/2" inch from the original damage is a permanent part of the car. It's not coming off - YET. As the panel continues to rust it will do so UNDER the filler and continue the "popping". The filler that failed is a result of the bodyman not removing every molecule of oxidation from the scratch, sealing in the moisture / oxidation with filler, and letting it continue munching on the 1/4 panel under the filler. As the rust continued it had nowhere to go , so it split the improperly bonded filler. Total thickness of this repair, about 3/16" at the crease of the dent/scratch.

Tony, I said it will not fail when properly applied, and I will stand by that. All the examples you gave are with improper application, period.

The car below is my brothers. It is STILL after 10 years in show condition. I am not talking, "looks good enough to park at a Goodguys event" I am talking good enough (with some detailing) to park next to ANY car there and still look good. No failure, no "Bulges", no cracking, NOTHING.

And if you were to see about 95% of the show cars out there before priming, you would see the same thing.
I am sorry, if used properly, quality plastic fillers WILL out last everyone reading this and their kids, and grand kids.
http://members.aol.com/icantunderstand/roadsterinbondo.jpg
http://members.aol.com/goodstuff53/arod.jpg

By the way guys, I didn't use my skim coat method in the same way as I do now. I did it, but not with the polyester putty all over as I do now. In fact, it blows me away to think of all the work I did on this car. Today, are you kidding? I would rough it out in 80 and polyester prime it. Well, maybe 120 and polyester prime it, just because it is such a special car. But really polyester primer won't shrink even with the 80 scratches. I would just have a hard time not finishing the filler off in 120 before priming with the polyester. The thing is, even doing that, as you "rough" the filler out you wouldn't worry about pin holes or flawless flat panels, you could use the polyester primer for that.

LOL smile.gif as I am typing this saying I would just spray the polyester primer, now I am not sure if I would, I would probably just go ahead and use the skim coat method with polyester putty and finish it off for urethane primer just like I did back then. Or in the very least, finish it off the same way, but polyester prime it just to block it out and urethane prime it on that. Anyway, at least I have pointed out another way. It could be a choice for you, use the polyester primer as a skim coat.

You want to see some filler?Look at this car.

photo 1 (http://f1.pg.photos.yahoo.com/ph/ochrisl/detail?.dir=/other+stuff&.dnm=428c.jpg)

I did this one a few years ago. The fenders were so battered i worked the metal the best i could and coated all the the fenders(and much of the body) with Rage,Then a lot of polyester prime.Still looks good today. If you have ever worked on or saw a street rod being built,you would see that the body is usually covered from one end to the other with plastic filler.It is neccesary if you want an arrow straight body.Its the only way on heavily modified or just plain beat up old metal. somewhere i have photos of a chopped Ford delivery i did that was solid plastic,not one piece of metal showing before it was primed.It is quite a sight.(i just blocked it and painted it,someone elses handywork) :rolleyes: If its done right and not TOO thick it will last. I have abused it before i knew better and have had it last quite a while.

i agree with Martin sr. i did the quarter panel and front fender on an 87 accord when i was 15.... the quarter i didn't prep as i should and i used bondo to patch a hole.. now rust it starting to show thrugh.. but the front i took down to bare metal and prepped the area properly, i laid a thick layer of bondo over it and its still holding out perfectly with no signs or failure... even after being abused over the years still looks like i just did it not long ago.. i sprayed the back of the repair throughly with rubber undercoating paint to keep moisture away from the repair...

I agree with the cure time on the filler, I'm sure solvents are being released for 10 hours or so. Polyester filler sure gets a bad rap from the butchers out there using it to booger up cars, I've never seen a product failure with polyester only improper usage causing problems.