(help)Skip fiberglass cloth and just bondo?

[Skufire]

Just wondering if its at all possible to just cover the armor pepakura piece with resin, and then when it dries, bondo it. would that work and save time from putting fiberglass cloth? or is the cloth essential to the piece?

 

[Spitfire22V]

No, the cloth is essential, as that is where the strength comes from. Fiberglassing is a classic composite material, in which 2 different constituent materials are combined to form a compound that is stronger than the sum of its parts. The combined materials have specific names, namely the reinforcement, and the matrix. In this case, the fiberglass cloth itself is the reinforcement material, or the foundation/main structure of the composite. The resin is the matrix, which serves to bond the fibers of the reinforcement and cure it into a hard structure capable of supporting loads and stresses.

So, no, you will get very little, if any, strength from only resin. You need the cloth.

 

[LoneHowler]

I'm just a noob I'm only on the pepakura stage of my build. But I watched a series of vids where a guy just used resin and rondo.

I'm considering trying this myself

 

[TD2253]

What I did with my helmet is resin the outside, then brushed/slushed rondo (half fiberglass resin/half bondo) on the inside of the helmet twice. It seems to be very strong compared to laying fiberglass matting. Then, I brushed on a thin coat of rondo on the the outside to get rid of pepakura seams and creases. So, in short I skipped laying fiberglass down and used rondo instead to strengthen my helmet. It's a faster process which will give your pepakura model the strength it needs to be worked on with bondo without warping or tearing the model.

 

[Drgnfyre4]

You can also use fiberglass resin on the outside, and then slush cast urethane casting resin on the inside. I usually do about two good coats of the fiberglass resin on the outside to have a nice sanding surface. I slush cast the urethane resin on the inside evenly and my pieces can withstand being stood on by all 250 pounds of me. Mind you I use really good casting resin from Silpak which is what is used on film industry props.

 

[Swift]

Basically, you will always have to do some reinforcing on the inside, whether it be matting, rondo or something else. The outside of the piece is purely aesthetic - if the inside is not designed structurally sound, then it won't be able to support itself.

 

[CoolC]

You need to pick one, either rondo or fiberglass, but you can never skip this process. I've used rondo and fiberglass, and I can tell you both have pros and cons. Fiberglass is very hard to work with. It is almost impossible to make it conform to the inner cavity of the helmet, especially those tight spaces. While most can attest that Rondo is stronger, I would beg to difer. I've used rondo on my kids' ODSTs and I noticed that it is susceptible to crack. While I wouldn't test this, but I can imagine the end result. If you drop a helmet done in Rondo and another done in Fiberglass from a 3 floors building, the helmet in Rondo will likely to crack.

The solution, use both. Slush Rondo inside with just a coat. Once dried, apply fiberglass on large areas to strengthen it.

 

[Erikm1811]

I would second CoolC's idea to use both, that's what I'm doing on my Jorge build, and it seems to work well so far. All results will be posted in my build thread.

 

[Jason 078]

If you are crazy, like me, you can use other materials than cardstock to build your pepakura. For me, I am using PVC foam board (aka sintra). Sintra has a greater strength and can be bent with a heat gun and folded with scoring lines. However, even then, you will need a good resin inside the piece.

One of my friends did a snowtrooper helmet with this method but felt that a light later of bondo inside would be enough. His helmet was accidentally knocked off of a chair while suiting up for a troop and it shattered like a crystal into almost all of the individual pieces it took to build the helmet.

In short, no matter the material (well, unless it is steel), you will need to reinforce it with something other than bondo.

 

[CoolC]

One of my friends did a snowtrooper helmet with this method but felt that a light later of bondo inside would be enough. His helmet was accidentally knocked off of a chair while suiting up for a troop and it shattered like a crystal into almost all of the individual pieces it took to build the helmet.

Ouch! Your friend probably sat down not believing it. Did you offer him something to wipe his tears?