What to use to fill imperfections on bondo?

[tauriice]

I've pepped several helmets, but they never turn out as smooth as I would like. I do the typical cardstock covered in resin and bondo but there are always inevitably small holes and imperfections which I can not smooth out no matter how much time I spend sanding and filling with layers of bondo. I've used the glazing and spot putty, but that still leaves little pock marks and imperfections. I just really want a nice, smooth helmet that I can maybe mold and cast some day. What do you guys use???

 

[prostheticsoul]

Spot Putty should do the work. Maybe you are doing something wrong with it.

 

[Murdoch]

What grit of sand paper are you using? Mixing the bondo better will eliminate the air pockets...GM

 

[tauriice]

I use several grits of paper, usually start with 80, then down to 120, then 220. Maybe I'm just not applying the original layer of bondo right. I haven't found a great technique yet.

 

[prostheticsoul]

What i do (and its what i learned and its MY technique maybe someone does it differently) Is that i don't cover the helmet completely of bondo at once. I go by parts with thins layers of bondo because once i apply the bondo then i can sand it better before it hardens to hard

 

[ManitobaMando]

As above, that is my preferred method as well. Do a thin layer at a time. You do not need to glop the bondo on and spread it around. Small amounts, spread thin, layer by layer with light sanding in between helps cut down on those air pockets. Also the glazing putty helps after the fact as well. Aain you dont ned to glop a huge amount, as with the bondo, light layers. For those incredibly small pock marks, use a filling primer paint and do a couple of coats, then for a REALLY baby bottom smooth finish, sand over that primer with 600 grit.

 

[tauriice]

I'll be trying some of these methods. Thanks guys.

 

[Talaaya]

If I had to guess, you may just be mixing your bondo in a way that introduces air bubbles and those are what are causing the pock marks. This video taught me how to mix bondo.

Also, when you apply the bondo, try to press it into the surface with your spreading tool so you really get it in those imperfections. Lay it on too light and the bondo will just hover on top. It has a pretty high viscosity after all.

Hope that helps!

 

[Coolc]

Try my technique. I have a video on YouTube using sunlight/light and bondo.

Halo 4 Tutorial - Bondo to Perfection - YouTube

Hope that helps.

 

[FirstAvenger]

It is DEFINITELY your technique.

Want to fill pock marks in bondo? use bondo. If it isn't working yo aren't mixing it right or something. I've used bondo in car repair for years and gotten smooth as glass results with it, no problems.

And you don't put it on thin and work it up, you apply a generous coating of bondo, spread it well filling all the areas you need filled and cut it down gently with your trowel/tool that you are using to shape it with. One hardened, work it in broad strokes, evenly and with equal pressure. Heavy grit to shape and cut down areas, then refine it to finer and finer paper as you go down.

You should end up with a perfectly smooth surface with ZERO pock marks or bubbles.

It just takes practice.

 

[TheOne1111]

When I bondo, I feel like I just keep running in circles. I don't get air bubbles, I get really ugly indents like I was digging at the bondo with my finger nail or something. I'll get one part really nice. Move to another and then when I come back, it's not smooth, wet bondo fingerprints got on it, etc. fix that up, other side is ruin, ad nauseum. Lol.

Getting a finer grit paper worked for me (can't remember the number but it was highest they had at hone depot when I went. 400's maybe?) but I think if you went much higher, it'll work out tremendously for you, along with a nice filler primer spray b

 

[made007]

I start with 40, then 80, 220 dry then 320 wet, and you should see my builds
I use red spot putty and white putty if you need more info let me know

 

[FirstAvenger]

When I bondo, I feel like I just keep running in circles. I don't get air bubbles, I get really ugly indents like I was digging at the bondo with my finger nail or something. I'll get one part really nice. Move to another and then when I come back, it's not smooth, wet bondo fingerprints got on it, etc. fix that up, other side is ruin, ad nauseum. Lol.

Heh heh...

Yeah, all that is typical noobie mistakes. It gets easier. It just takes a lot of practice. I wouldn't even want to show pictures of some of my early body work and how badly I messed it up. And it took hours to get a perfect cluster f out of it.

Today I can do a whole quarter panel, smooth as silk in no time at all and make it look stupidly easy.

Practice practice practice.

 

[TheOne1111]

Heh heh...

Yeah, all that is typical noobie mistakes. It gets easier. It just takes a lot of practice. I wouldn't even want to show pictures of some of my early body work and how badly I messed it up. And it took hours to get a perfect cluster f out of it.

Today I can do a whole quarter panel, smooth as silk in no time at all and make it look stupidly easy.

Practice practice practice.

Oh my god. Most annoying thing ever. I didn't use very thick coats. They were really thin and nice, but it tools *days* to get my helmet nice, but there are still all of these imperfections. I eventually just said, "That'll do." and I'm going to make the imperfections look like scratches and battle damage, but next time, I'm hoping to get it really smooth.

I feel like I've thread-jacked enough, so I'll just step aside now. Haha.