Help With Sanding Bio Mask

[Phonemonkey]

Hi Guys,

Just looking for some guidance. I've built my Pepakura mask, used car body filler (Bondo) and got it what I perceived to be uniformly smooth.

I just gave the mask a coat of spray paint primer and it now looks like a map of the Moon with lumps and bumps and the occasional pinhole dotted about.

I sanded back again and applied body filler to the parts thet were really prominent, sprayed it again and it now looks even worse. You can see a clear distinction between the sections that have had another layer of filler and the bits that haven't.

I am smoothing it dowm using different grades of sandpaper (150 being the finest I've got) but to no avail.

Am I doing something wrong? If I painted the mask further would a lot of the lumps be hidden? Ant tips or suggestions?

I am planning to make a mould of this and want it as smooth as possible but starting to get discouraged with this constant sanding what seemed to be smooth in the first place.

Again, any help would be appreciated.

 

[TuaCathach]

when your sanding the filled sections down are you just concentrating on those sections or going over the entire mask? also are you making sure the are you filled is sanded down to the same level as the original piece, so that they blend.. the stage you are at now is probably one of the most time consuming parts of your prep work.. take your time at it and just keep going until you get it right

 

[Phonemonkey]

when your sanding the filled sections down are you just concentrating on those sections or going over the entire mask? also are you making sure the are you filled is sanded down to the same level as the original piece, so that they blend.. the stage you are at now is probably one of the most time consuming parts of your prep work.. take your time at it and just keep going until you get it right

I'm concentrating more on the filled sections but obviously trying to blend them in. Sould I go over the full mask? I don't want to lose the "Shape" of the mask by sanding down an already smooth area. I'm finding when I have done this, it seems to make the lumps and bumps of the newly filled sections even more prominent.

 

[wonko]

What are you using to fill the spots with? It's been my experience that spot putty is the best and only way to ensure all those pin holes are filled. Also, depending on the brand of spot putty, it sands easier than the body filler. I've been playing around a little bit with molding lately, and it's been my experience than any little flaw is gonna show up in the silicon. As was posted earlier, the sanding is the most time consuming and important step in producing a quality piece, so take your time. The final outcome will be worth the effort.

Brian

 

[Phonemonkey]

Yesterday I filled in the nicks. and pin holes with milliput. Feeling a bit more confident about the outcome now. As Wonko says. easier to sand than body filler and I'm getting a more uniform smoothness.

Think the initial post was more out of frustration than anything else. You think you have finished sanding and, lo and behold, one coat of primer later and you're back to square on.

Thanks for the advice, guys. At least I know I am going about this the right way.

 

[wonko]

I use that first (and usually second, third, etc.) primer coat as a guide to help me see what still needs sanding. Make sure you have the kind of primer that you can sand and you'll be good to go.