mrazntre
08-30-2002, 12:53 PM
Has anyone ever experienced the joys of bondo? (Bondo is actually a mfg's name for the substance known as body filler... more info here (http://www.bondo-online.com/Default.asp))
I'm straightening out my body right now, so I'm well immersed in the joys of bondo. Bondo is basically a rigid (altho there is some degree of flexibilty) type of "plaster" that is sandable and paintable. Bondo is not only used on sheetmetal work, but can also be applied on wood surfaces, just like plaster, aka mud, spackle, or any other fix-all type of repair putty. I digress.
There are two elements in Bondo, you have the greyish paste and the cream hardener which is red in color. Instructions say to mix a quarter paste with a quarter hardener. However, depending on what area (or what type of dent) you are working on, you may want to add a little more hardener or paster, whatever the case may be. More hardener equals less work time, and vice versa. But you must keep in mind that too little hardener will result in a mixture that will not harden properly, and will just cake off during sanding.
If you've never worked with bondo or plaster before, it's pretty easy to work and do an okay job. To do a perfect job takes countless hours of practice and most importantly, patience. For a tiny ding, I'd suggest you leave it alone, because a half sprayed car looks like shit (just take a look at my car). If you're working on a car that looks like it's been thru a few battles, then I say, go ahead and start sanding. For whatever dent you're working on, always bang out the dent (if it is significant enough --- you're only supposed to apply about 1/4 of bondo to fix. (you can actually use more, but applying more than that creates problems such as cracking). so get out your ballpeen hammers and start banging. There are a lot of specialized hammers to work with cars, but I just use my Electricians hammer, and a small lady's hammer. A ballpeen hammer actually has a rounded head, as opposed to the flat head of a traditional hammer). When you bang out the dent, don't worry too much that the paint is cracking and you're creating sharp marks in the sheetmetal. Just be aware that you're not hammering those points beyond where you would like to bondo. After configuring the sheetmetal close to its normal shape, proceed to sand the area. Bondo sticks better to metal so sand it all the way down. Or you can be like me and just sand down as good as it feels and hope for the best. Always clean the sanded area with a wipe cloth (dampened with alcohol preferred to clean up the rest of the dust).
After mixing up your bondo mix, you're ready to be an artist. I usually use the cap as my mixing palette, but it gets pretty dirty. Mix with a screwdriver or something clean. Make sure the mix is one color before using. To apply the bondo, I use an assorted variety of flexible plaster knives (go to Home Depot). 4" and 6" are good sizes to have. Also a big 1foot would be good for large areas. Remember that applying bondo at first is a very rough thing... just smear it on the affected area, don't try to sculpt it so much the first time around. Just fill the dent adequately.
Next, you will need a wood shaver (or a body filler shaver -- it's basically a cheese grater, you can get this at Autozone or Home Depot). After the bondo has initially hardened, just feel it, you can start to tell. Shave away! Use long strokes, back and forth. By shaving, you get rid of the excess and start to shape the bondo into the sheet metal. This is a very rough stage, so grind out as much bondo excess that you can. Let it harden some more, and then you can proceed to actually sand the bondo. Always use a sanding block (this is not always possible, but use it as much as possible to prevent dips). Use long strokes. You want to use the straight sheetmetal to guide your sanding block so it will straighten out the dented area that you are bondo'ing. I would say to use something like an 80 or 100 grit sand paper to initially knock down the bondo that you have just grated. Then when it starts to form more, I would jump to 180 grit, and then 200+ grit, then use progressively higher grit to smoothen the bondo (like 300). Granted there will still be dips from the grater, but still sand it smooth. Once the area looks more like it did before, clean the area and apply more bondo. You will have to remix the bondo because chances are the stuff on your palette is already hard and useless.
And just keep on repeating this process.
Once it looks really good (or if you have bare sheetmetal exposed and you can't finish...) spray the affected area with primer. Then, you'll have to sand and bondo again because the primer will guide you in looking for more imperfections in that area such as slight dips, high spots, low spots, and sanding marks. You want the area to be smooth.
I'll be back to post more, but that's the main thing to bondo.
I'm straightening out my body right now, so I'm well immersed in the joys of bondo. Bondo is basically a rigid (altho there is some degree of flexibilty) type of "plaster" that is sandable and paintable. Bondo is not only used on sheetmetal work, but can also be applied on wood surfaces, just like plaster, aka mud, spackle, or any other fix-all type of repair putty. I digress.
There are two elements in Bondo, you have the greyish paste and the cream hardener which is red in color. Instructions say to mix a quarter paste with a quarter hardener. However, depending on what area (or what type of dent) you are working on, you may want to add a little more hardener or paster, whatever the case may be. More hardener equals less work time, and vice versa. But you must keep in mind that too little hardener will result in a mixture that will not harden properly, and will just cake off during sanding.
If you've never worked with bondo or plaster before, it's pretty easy to work and do an okay job. To do a perfect job takes countless hours of practice and most importantly, patience. For a tiny ding, I'd suggest you leave it alone, because a half sprayed car looks like shit (just take a look at my car). If you're working on a car that looks like it's been thru a few battles, then I say, go ahead and start sanding. For whatever dent you're working on, always bang out the dent (if it is significant enough --- you're only supposed to apply about 1/4 of bondo to fix. (you can actually use more, but applying more than that creates problems such as cracking). so get out your ballpeen hammers and start banging. There are a lot of specialized hammers to work with cars, but I just use my Electricians hammer, and a small lady's hammer. A ballpeen hammer actually has a rounded head, as opposed to the flat head of a traditional hammer). When you bang out the dent, don't worry too much that the paint is cracking and you're creating sharp marks in the sheetmetal. Just be aware that you're not hammering those points beyond where you would like to bondo. After configuring the sheetmetal close to its normal shape, proceed to sand the area. Bondo sticks better to metal so sand it all the way down. Or you can be like me and just sand down as good as it feels and hope for the best. Always clean the sanded area with a wipe cloth (dampened with alcohol preferred to clean up the rest of the dust).
After mixing up your bondo mix, you're ready to be an artist. I usually use the cap as my mixing palette, but it gets pretty dirty. Mix with a screwdriver or something clean. Make sure the mix is one color before using. To apply the bondo, I use an assorted variety of flexible plaster knives (go to Home Depot). 4" and 6" are good sizes to have. Also a big 1foot would be good for large areas. Remember that applying bondo at first is a very rough thing... just smear it on the affected area, don't try to sculpt it so much the first time around. Just fill the dent adequately.
Next, you will need a wood shaver (or a body filler shaver -- it's basically a cheese grater, you can get this at Autozone or Home Depot). After the bondo has initially hardened, just feel it, you can start to tell. Shave away! Use long strokes, back and forth. By shaving, you get rid of the excess and start to shape the bondo into the sheet metal. This is a very rough stage, so grind out as much bondo excess that you can. Let it harden some more, and then you can proceed to actually sand the bondo. Always use a sanding block (this is not always possible, but use it as much as possible to prevent dips). Use long strokes. You want to use the straight sheetmetal to guide your sanding block so it will straighten out the dented area that you are bondo'ing. I would say to use something like an 80 or 100 grit sand paper to initially knock down the bondo that you have just grated. Then when it starts to form more, I would jump to 180 grit, and then 200+ grit, then use progressively higher grit to smoothen the bondo (like 300). Granted there will still be dips from the grater, but still sand it smooth. Once the area looks more like it did before, clean the area and apply more bondo. You will have to remix the bondo because chances are the stuff on your palette is already hard and useless.
And just keep on repeating this process.
Once it looks really good (or if you have bare sheetmetal exposed and you can't finish...) spray the affected area with primer. Then, you'll have to sand and bondo again because the primer will guide you in looking for more imperfections in that area such as slight dips, high spots, low spots, and sanding marks. You want the area to be smooth.
I'll be back to post more, but that's the main thing to bondo.