thinning bondo with fiberglass resin

You cant spray bondo!

 

I take it all back. You can spray Bondo brand products. 3M sells SPRAY Bondo brand products and the spray guns. Both battery operated and air operated. Many different applications and sizes available. Comes in 1 quart to 5 gallon and larger containers.
Don't I feel dumb.

http://solutions.3m.com/wps/portal/...79D02R7QH2A20CJ7_nid=4GB9HXB7J4beXPZ854VZB4gl

 

This thread is a perfect example of what happens after you shoot for years without a respirator...

 

Because he is too cheap to buy the right products for the job.

http://www.jalopyjournal.com/forum/showthread.php?t=617680&highlight=high+build+primer

 

Guys, you have tried to guide him in the right direction.
It is apparent that the only way this is going to sink in is for him to experience the frustration of trying this method.

I have the recipe for making polyester body filler, and access to the materials, and I buy it ready made in the can. I can't make it any cheaper, or any better.

 

Ok, OK,

You can thin body filler with surfboard resin. The reason you do this is to build up a panel for block sanding quickly without the shrinkage later on often found with high build primers as they dry out. I know a very very talented journeyman who does this and also several other great bodymen/painters which do this. It's an old trick which avoids some of the pitfalls of using 30 coats of primer filler on a panel. Primer filler is great but will shrink over time and leave a bummer of a situation if applied incorrectly and too thick. Thinned Filler is easier to spread and gets there faster.


But the trick is to staighten the panels first so minimal filler is needed, That's what should be done. Spend the time on the metal and you won't need to put the perfume to the pig. Having said that most cars even the best baremetal ones have the equivelant of a skim coat over the whole thing wether it be filler primer or thinned filler. You gotta block sand something so it a pick your poison type of deal.


But for God's sake man if you gotta spray it you need to be a sculpter or a Boat builder not a bodyman!



Good luck,

Tim

 

Those are great products...if you are installing traffic signals in/under pavement.
I like the "Sausage gun"

 

The only reason I can think of for spraying it would be to fill the inside of a mold for a cast type of part. Which would be great until the first good whack, then shatter like a safety-glass window.

 

Wow. Let me first start with your question about thinning plastic body filler (Bondo has become a generic term, like "Scotch Tape", and "Band-aid", so I'm going to call it plastic filler, OK?) so as to spray it.

NO. You cannot, as the people who's opinion you want ignore are saying. You can however, thin polyester (plastic) body fillers meant to sprayed, with acetone or laquer thinner to help spray it, usually up to 10% or so. EverCoat's "Featherfill" is one, I've used it for years with good results. I have heard people, ill-informed people, describe this as "spray Bondo", so perhaps that's what you heard as well. There are product use directions on the back of every can (believe me, I've looked at a lot of 'em) and spraying it is NOT on any of them.

Second, free advice on the inter-web, (or, this great system of tiny tubes that connects us) is generally worth the price, but trust me, I wouldn't lie...

Third, what's up with the attitude? Your question was answered in the first couple of posts, and now you seem to pissed that nobody agree's with the hare-brained idea. Instead of copping a 'tude, trot on down to your local bookstore, and pick up a copy of a basic text on auto-body work, or go to Amazon and pick one. It'll be chock full of authentic, real-world advice that you can refer to for years. That's what I did almost 40 years ago, and it was invaluable to me.

Brian

 

It is actually MEKP. I can't remember what the P stands for, but the resin won't catalyze if you just use regular methyl ethyl ketone.

For the guy who wants to spray Bondo, just mix up a small batch and start adding acetone until you get it thin enough to run off the end of a mixing stick. I'm curious to see how it works, let us know how it works out and if you get it all out of your gun before it kicks.

 

What you are looking for is called Polyester Primer - a polyester based sprayable product.

I don't recommend making your own by thinning bondo! - you never know what will happen once it ages and you have paint on top of it. The polyester primers are basically resin and polyester filler, and I am sure they are formulated for the purpose.

I used it use it on older corvettes where the fiberglass was brittle and porous, and I once stripped a 1970s Ferrari that had a handmade body that was a bucket of waves from the factory with a THICK coat of some kind of epoxy primer on it. We had to spray it 3 times with the Morton Eliminator and sand, sand, sand until the body was straight.

here are links to some polyester primers

http://www.google.com/products/cata...a=X&ei=q01UToW2IabE0AHBms2gAg&ved=0CC8Q8wIwAQ

and good old Morton Eliminator

http://www.eastwood.com/usc-high-bu...chant-Centre&gclid=CI_e9qve5qoCFcU65Qod81pg7A

These are primers that you mix with hardner and blocksand, the hardner is methyl/ethyl/ketone - same as used in fiberglass resin and body filler, and the primer must be mixed very well - when you get it it is 3/4 filled with a clear resin (fiberglass resin) with more solids (bondo) at the bottom. Mix it good - for like a 1/2 hr to make it all uniform - add the hardener and spray. if you forget to clean your gun right after - plan on throwing it in the trash!

 

Lmfao!

 

after someone tries I want to see photos!

 

Let see if we can put the question to rest .
The early versions of "bondo " didn't spread easily , were not very flexible, were prone to cracking , pinholed easily, the hardness of these early materials made leveling the cured material like sanding bricks. One of the old tricks was to add a little resin in your last coat of filler to lessen the pinhole issue and to make it spread out a little nicer. How much you would add would vary on how thick the left over stuff in the can was. The early "bondo" formulas tended to separate and the resin would float to the top of the can and the solids to the bottom. Most body guys would not take the time to remix the contents well and as a result the bottom of the can could be like concrete. So to salvage the costly material resin would be mixed in to save the remaining product. It in no way overcame any of the early material shortcomings or sloppy application methods . This was the state of the art of plastic resin technology of the time in the 50's and 60's . As chemistry and resin technology advanced the plastic fillers improved into what we have today.
The "bondo " makers have listened to the gripes of the bodymen and worked with them to make better products. Today we have bondo straight out of the can that is near impossable to get pinholes in and doesn't easily separate. There are "bondo " fillers today that come in several different viscosities which for the most part eliminate the need for mixing in resin to the "bondo". If you figure what a quart of resin cost today against what one of the thinned "bondo" fillers cost your not really saving any money or time.

As said by several others earlier if you want to spray bondo buy "featherfill". Which is basically thinned catalyzed filler that sprays through a paint gun. Many of the guys myself included have been in the Body Shop business for decades and speak from professional experience .

Hopefully that will fill in the missing blanks .

Now lets go see if we can learn anything from old Red as he chops a top .

http://www.youtube.com/watch?v=TCISlfory98

 

I know, but dude refuses to tell us what he wants to use it on, so that's the info he gets. He needs the sausage gun......
He's a mess, he has this thread going as well:
http://www.jalopyjournal.com/forum/showthread.php?t=617680

 

On a related note, I have some really thin fiberglass resin and was wondering if I could thicken it with Bondo.................

 

I am starting to think this guy is on here just to fuck with us.

 

Somebody PLEASE just tell him how many quarts of cheap flat black it will take to paint his car and make it stop!!!

...makes my head hurt to see so much good advice get totally ignored....

 

I really envy some people at tax time. Imagine the fed tax breaks for this level of....uh.... Special person.

Oh yeah, I think 28 quarts should be almost enough paint.

 

Yes, yes....MEKP or MEPK. I knew i left out a letter. Thanks !!

 

Do yourself a favor, if the word Bondo is on the can, don't buy it. Get some real professional-grade product.

 

Thank you msalamanca
No more needs to be said.
Now I'm on to more important posts.

 

Body filler is polyester based. "Regular" fibergless resin is polyester. While it might be possible to mix the two and spray it, that isn't necessary. Spray on polyester fillers have been available for years. "Feather Fill" is the most popular brand, but numerous others exist. The ones I liked best are no longer made, and at this point many have switched from Feather Fill type products to urethane surfacers. There are advantages and disadvantages between the two products, but that's another discussion.

While perfect metal finishing is the ideal, there is the matter of time and practical reality. When properly used there is nothing wrong with using a high build surfacer. It is a routine step in prepping a show car for paint. Even the hand made bodies on old classic cars had a layer of surfacer under the primer and paint.

 

MEKP = Methyl Ethel Keytone Peroxide . (please excuse any spelling misteaks)

 

OK, I'm one guy who tried to thin plastic filler with acetone and spray it. I came up with this idea after my neighbor used a heavy build two part spray primer. After he sprayed it his garage smelled like plastic filler. I found one of the components of filler was acetone so I used it to thin it. I thinned enough to spray and added the hardener that came with it. I tested this on a couple of scrap pieces of sheet metal to see how it worked. I used a regular spray gun, nothing special. On the test pieces the filler hardened in about the same time as normally mixed filler and I was able to sand it very easily. I then sprayed a door and the stuff refuse to harden, even after letting it sit for a few days. I ended up scraping it off. I probably didn't mixed it exactly like the first time, I was probably just lucky the first time. IMO it's not worth doing, go with the proper product.

 

MEKP is usually used with polyester resin for lamination with fiberglass or carbon fiber. Plastic fillers commonly use BOP paste (benzoyl peroxide). Either one will work, but MEKP mixes easier into resin, and BOP paste mixes easier into fillers. The filler, or the resin, commonly has Cobalt Octoate, or Copper Octoate to combine with the added catalyst to start the curing process.

 

I have always found it amusing that filler hardener is a stronger concentration of zit cream.

 

If you want to spray bondo you should probably use a drywall hopper, or one of those machines that they spray grass seed along the hillsides with. Hope this helps............just kidding everybody relax.

 

Man, I think I have meet potatoes smarter than this guy!

Doc.

 

http://www.sherwin-automotive.com/products/show_product.cfm?product=FE1249