help needed for sanding

[kumba]

I need help for sanding. After peping resing and bondo my helmet i hit the sanding part and i prety much know what to do (sanding, sanding, and some more sanding) but after all that i come to a part where i have some small inperfections and i just dont know what to do how to smooth them. Picture is worth a thousand word so here it is pls some tips.

 

[CoolC]

This is where spot filling comes in. Mix a little bondo and fill in those spot sparingly. Just enough to fill the hole. Once you are done with the filling, you sand again.

 

[Katsu]

You can alternatively buy spot putty, which was designed specifically for this purpose. Bondo needs to be mixed, and has pot life and other concerns, where-as spot putty is just squeezed out onto the area, then smoothed over it.

Here is a fantastic video on spot putty:

However, I am under the impression that it is not quite as durable as bondo, but bondo isn't all that strong anyways, so if chipping is an issue, it'd be an issue for the bondo too, and you'd be wanting to mold cast it, or spray it with something protective.

 

[zacic]

agreed, spot putty or "finishing putty" here in Canada is specifically designed to fill in the little pits and divits, and its tinted a bright red so you can see where you have filled and give a definition that helps you see the imperfections.

 

[Prettyfloralbonnet]

Some of the bigger pits like what's circled at the bottom would likely need some regular bondo but I agree that the spot putty works wonders for everything else as a finisher.

 

[Katsu]

The whole area around the "mouth" thing needs to be sanded and filled a bit more in general, those narrow areas can't be reached by a sanding mouse, so you have to just use the sandpaper directly, and be very careful not to create grooves from oversanding one spot.

The forehead and beneath the eyes should be easily spot puttied.

 

[kumba]

Thanks all for responding, tonight ill try to put some more bondo on those spots and sand it hopefully that will do the trick as i cant find to buy spot putty anywhere. Thanks once more.

 

[Katsu]

Depending on where you live, most automotive stores will carry spot putty.

http://www.amazon.com/Bondo-907-Gla...M8PY/ref=sr_1_1?ie=UTF8&qid=1328690873&sr=8-1

Very cheap and very very easy to use. If you aren't in North America, it might be a bit harder to come by.

 

[golem95]

sorry but can someone explain the difference between bondo and spot putty to me? because I swear that if you apply bondo in the same way as spot putty it too should fill in those little pot holes on the surface no? I use a pallet knife to spread my bondo on nice and thin and spread it into the little holes

 

[kumba]

Thing is im in Bosnia and its a bit hard to find anything here it took me almost a month to find polyester resin, spot putty i dont expect to find but i will try (funny i was even considering clay) but that could hold my work and that we cant allow . Anyway thanks!

 

[golem95]

try finding wood filler, its like a white paste that i use, its air drying so you need to keep it closed when not using it tho.

 

[kumba]

hey i just did that i have friend who is in arts school so i asked him and he said the same thing so i went to shop and bought it i hope that wood filler would do the trick. Thanks again.

 

[golem95]

just make sure you have something like a pallet knife to really spread the filler into those gaps, you needa use a bit of pressure to make sure the filler completely fills the space but not too much pressure as to scratch the surface of your prop

 

[kumba]

something like credit card will do i guess?

 

[Abaris]

Thing is im in Bosnia and its a bit hard to find anything here it took me almost a month to find polyester resin, spot putty i dont expect to find but i will try (funny i was even considering clay) but that could hold my work and that we cant allow . Anyway thanks!

Any wall repair putty will do the work.

 

[golem95]

yeah credit card would do although i wouldnt use mine to work with pallet knives are easy to find, most hardware stores will have them

 

[kumba]

well i have old game card from world of warcraft so that will do coz its same size and material as credit card if not im sure i will think of something.

 

[Spitfire22V]

sorry but can someone explain the difference between bondo and spot putty to me? because I swear that if you apply bondo in the same way as spot putty it too should fill in those little pot holes on the surface no? I use a pallet knife to spread my bondo on nice and thin and spread it into the little holes

Spot putty doesn't have to be mixed the way that Bondo does. It's simply a small tube that you squeeze out the proper amount, instead of a tub. I'm not entirely sure why it can't be used on larger surfaces in place of Bondo, but as I understand, it's really only best suited for filling small imperfections, most likely due to it's sanding and strength properties. i.e. For the same area, Bondo is structurally stronger, but the spot putty is just more convenient instead of mixing up tiny amounts of Bondo for touching up.

 

[ventrue]

something like credit card will do i guess?

I tried that, but it didn't really work that well. Those cards are too flimsy in my opinion.

 

[Katsu]

sorry but can someone explain the difference between bondo and spot putty to me? because I swear that if you apply bondo in the same way as spot putty it too should fill in those little pot holes on the surface no? I use a pallet knife to spread my bondo on nice and thin and spread it into the little holes

The problem with bondo is it very thick and putty-like, which makes it harder to force it into small holes.

Spot putty is mainly different because it's a one part process, where body filler (bondo) is a two-part process meaning you need to mix a batch every time you want to use it, and it has a pot life. Spot putty is very nice to work with mainly because a) It won't harden until it leaves the tube so it can be used on demand, b) It doesn't need mixing again nice for on demand use, and c) It is substantially smoother to work with as it is less like putty and more like cream in texture.

But if you prefer working with bondo for this application, that's fine too! Whatever you are most comfortable with is best.

Edit: I didn't realize there was a second page and the question had been answered when I posted. In response to him though, the downside to spot putty is it isn't as strong - which doesn't matter when filling cracks, and is much more susceptible to sanding (which can be good or bad, depending on the use, good for filling holes, bad for covering a big area)