Bondo, how do-eth I?

[Anonymous]

greeting fellow GS enthusiasts. I am in the middle of remodelling my gs 400, appearance wize. I just finished sandblasting the fuel tank, and i have the new side covers (not painted) ready to go. Turns out i have a few good dings in my tank. I have been told to body fill these in with Bondo. I havent bought the product yet, but my question is, will this 'bondo' adhesive stick to the bare metal? do i have to prime it? is there a certain and particular process? any help would be appreciated for it is set to be painted tomorrow

ps. i will hopefully have before and after pics in a week

[Billy Ricks]

Most fillers like Bondo are meant to be applied over bare metal. After priming if the filled area needs a little help use lacquer putty. It's great for pointing up, sands easy, and doesn't cause the paint to flash. Reprime the spots you refilled and your ready for base coating.

[Anonymous]

It's not all that hard to do but it takes time to learn. I'm not too sure about surface preperations but I just sand everything it is going to touch.

Mix it as per directions on a piece of flexible plastic. Then slop it over the damaged area wait for it to get hard enough to sand it, do not wait a long time as it becomes impossible to sand by hand. If it isn't right slop on some more over the last pile and try again. As for the contour, bild it up high in the middle of the damage and taper it off a few inches past the blemish. That way when you sand it down you get a smooth transition. I think I'd just pay the painter to do it if he's a pro...this stuff is a real pain. I only do it when I buy cars as I'm just trying to fill in the holes for a safety.

Steve

[thomastedder]

If you want it to last, go to bare metal. DON'T "slop it on". Use very thin coats. When you mix it be careful not to get air bubbles in it. Don't mix much as it won't take as much as you think. Put one thin coat on. Sand it with 180 or 220 grit sandpaper. It is important to use a block. On gas tanks (because of the contour) I like to use a foam block. You can get these at your local paint store. Sand it from several different angles until the edges smoothly transition with the rest of the tank. Put another coat on. As it you build it up use your spreader to sort of match the contour of the tank with the bondo. Sanding is the most important part of doing bondo work. When you're done, run your hand along the tank completely over the bondo from every angle and make sure you can't feel where the bondo begins or ends. You won't be able to see flaws now, but you will when the paint's on. It's OK if it's not right. Put on another coat and sand again. By the way it's not impossible to sand when it's dry. That's when you're supposed to sand it. Before it's dry, but still partially cured, you can "shape" it with a "cheese grater" (also at the paint store). However, I prefer to use 40 grit sandpaper for shaping. After you prime it you have another chance to fix any flaws. Spray a light coat of rattle can paint on it. This is called a "guide coat". It should look like someone sprinkled pepper on it. Sand this with 320 grit. Make sure to use a block (very important). Sand until the guide coat is gone. If you sand through the primer anywhere, just reprime and repeat. When you get the primer sanded good, if there's any guide left don't worry. These are low spots. Also at your paint store is a product called "Piranna putty". Sort of like bondo, but much easier to work with and sand, but can be used on top of primer. Use a very light coat over the primer and sand it down. Close your eyes and feel. If you can't tell it's there, you're good to go. Reprime. Spray another guide coat and sand again. If you can sand all of the guide coat away without sanding through the primer you're now you're ready for paint. If this all seems a little too much, just read the directions on the bondo can. They won't lead you astray. Good luck.

[ard]

bondo

I have good experince in this field my family ran a bodyshop for a long time and I got to do some work there on antique cars.
for best results you need to create texture on the bare metal surfase to creat a bite, you want the bondo to sink in this rough surface that you can achive with a 24 grit gringing disc, be very carefull not to overheath the metal it get whorped make sure it is free of all kind of residue, and grease, including your pulm, make sure you dont touch the area you are going to fill with bondo, when you spread the bondo make sure you spread it slow with moderate pressure this methode will eliminate most of the pin holes that could me a headach to get ride of them after word.
if you have accessive bondo you will need a tool called chees grader, use that tool to get ride of the accessive bondo, get your self a rubber block for sanding, do not use your fingers you will create waves and youl get sea seek, use 36 grit sand paper to cut down to a point that you are sanding the metal around the bondo, change the sand paper to 80 grit, clean you hand from sweat, and run your palm on the work area, see if you fill any bumps, follow that pulm feeling you will find out if you over sanded or you need to do more.
once you deside it is smooth, get 220 wet and dry sandpaper and using the sanding block, featheredge the work area by sanding the bondo and the scraches that the 36 grit sand paper creates, once you make sure that your scraches are minimal, apply primer to the whole are by running the spray can or the gun way from the tank so you dont end up making primer dots on the tank. then use good quality acrylic putty that does not shrink apply the putty and let it dry very well.
get 360 or 400 grit wet and dry sand paper a bucket of water and a sanding block, and sand the work until it is smooth, spray primer one more time two wet coats are good, wait until it is dried, get 400 wet and dry sand paper and sand the prime, at this pint you can use you pulm to sand you dont need the sanding block.
If you are going to paint it yourself let me know I might give you some tips on spraying also.
Good luck be patiant with the procces, you l do good. the curvier is the panel the lesser you see the imperfections.

ard

[earlfor]

Ever see a patch after a year later on a car that has been filled with Bondo?
Rust stains around the bondo'd area, paint bubbling, discoloration. Bondo absorbs moisture and eventually the metal underneath starts to rust. I use epoxy resin with micro ballons mixed in as a filler if I am doing a job I want to last as long as the metal underneath. Epoxy adheres 20 times stronger than bondo. You can chip dried/set bondo off. You will not be able to chip dried epoxy off. Epoxy is moisture proof. Metal sealed in epoxy will not rust.

The sanding steps, preparation and painting steps are the same.

Earl

[thomastedder]

Ever see a patch after a year later on a car that has been filled with Bondo?
Rust stains around the bondo'd area, paint bubbling, discoloration. Bondo absorbs moisture and eventually the metal underneath starts to rust. I use epoxy resin with micro ballons mixed in as a filler if I am doing a job I want to last as long as the metal underneath. Epoxy adheres 20 times stronger than bondo. You can chip dried/set bondo off. You will not be able to chip dried epoxy off. Epoxy is moisture proof. Metal sealed in epoxy will not rust.

The sanding steps, preparation and painting steps are the same.

Earl

I have seen bondo after a year. After many years and I haven't done a bondo job yet that went bad. If you do it right it will last as long as the metal. I have seen some nasty bondo work. But, the product is only as good as the person using it.

[Anonymous]

If you put it on really thick it shrinks and cracks. I've seen 1/8" cracks on a 10-20 year old job. This was on a truck only used to carry grapes for 1 month a year so rust wasn't an issue.

Cheers, Steve