"Help!" for: Fiberglassing, Resin, & Bondo

[Katsu]

Don't blame the rondo for that one. It's a well established fact that many glues will dissolve when exposed to the resins in rondo/bondo/fiberglass. It is the fault of the chemical interaction between the glue and the chemicals, and has NOTHING to do with the order in which you lay rondo and fiberglass. In the future, use Hot Glue, PVA Glue, or SuperGlue, as they are established to NOT dissolve when exposed to the compounds in resin and bondo.

Additionally, I would not recommend fiberglassing the OUTSIDE of the helmet, this will obscure details and make modifying it a nightmare. While I applaud you for trying things to see what works for yourself, the conclusions you reached are not correct, and I'd like to help and keep you and anyone else reading from being confused by conflicting information, to save you future headaches when making your suit.

 

[Devohter]

Best way to re-align parts after bondo? It got warped a bit...sand it all off then re-apply?

 

[Katsu]

Was it hardened on the inside? Meaning is there rondo or fiberglass inside the piece?

Either way, it depends on the warping. But the beauty of bondo is you can do pretty much anything to the piece and cut away whatever, and then reapply bondo and get back to where you were. It's not like working with wood or stone, which are cut and you're done.

If you can easily sand/cut off the bad parts, do it, but try and retain the hardening on the inside of the piece (which SHOULD be there! If you haven't added rondo or fiberglass inside, you should do it ASAP)

Also, please post some pictures! It helps a lot more in figuring out the problem.

 

[ShadowCharizard]

Did a bit of thread-searching, and this isn't exactly addressed in the way that I'd like.

As a noob, I bought Bondo-Hair because I figured, "Hey, it's stronger than regular Bondo! That automatically makes it better, right?" Well...am I correct in thinking so? From the videos I've watched, it seems like Bondo is easier to work with than its reinforced Hair counterpart. Which is better in the long run?

ALSO, since it's stronger, should I be using a smaller ratio of it to fibreglass resin when mixing Rondo?

 

[Katsu]

Hairy bondo is used for people who are too lazy to properly rondo/fiberglass, really.
It IS stronger than regular bondo, because it has strands of fiberglass in it. But because of that, it's a pain to sand through. I also don't trust anything that has bits of other stuff mixed in it from a texture and consistency point of view. It's all personal preference though. If you already bought the stuff, you could give it a try and see if you love it or hate it. If it works for you, that's great! I tried it and went back to regular bondo, especially for the outside work.

My personal opinion is that hairy bondo tries to fill two roles and does a mediocre job of it:
1) It tries to be bondo, but bondo needs to be easily sanded and worked with, the fiberglass impedes that, and why would you need extra strength on the outside of the helmet? Hairy bondo makes sense for car repair in this instance, but not as much for halo suits, where ease of modding and smooth are more important.
2a) It tries to be fiberglass, but the bondo element makes it incredibly heavy and more brittle than just straight fiberglass which is VERY strong and light.
2b) It tries to be our own pet rondo. If you are rondoing for speed and ease of use, it's a mixture already and you won't get big strength gains from hairy bondo diluting it, so you'd might as well save some money and get regular bondo. If you are rondoing for a good strong system, you want to do a layer of regular rondo followed by a few layers of fiberglass. The woven fiberglass mat/cloth will be much strong and WAY lighter.

 

[ShadowCharizard]

Thanks for that! You, Katsu, are easily one of the most helpful people on the 405th. I used the Bondo-Hair on a practice piece I'm working on, and it does seem like a lot of sanding. I'm at least glad that I tried it out, though I feel like I wasted $50...

P.S.: Why would I want extra strength on the outside of the helmet? Because I like to jump around in my costumes :3

 

[Katsu]

If you want really easy to sand stuff, the Gold Standard bondo sands like butter. I ended up not using it because it sanded a bit too easily for my tastes, but everyone's needs are different.

And the PS, I did a super thick layer of just fiberglass on one of my helmets and stood on it, it's crazy what these materials (bondo, hairy bondo, fiberglass, etc) are capable of! I am sure you will make a great jump-proof suit.

If the hairy bondo works for you, stick with it. Worst comes to worse it can make for decent rondo stock, so you don't put it to waste sanding it off!

50 bucks? That's more than I was thinking it'd be, how much (volume or mass or whatever) was it? Normal Bondo is like 8-12 bucks a quart.

 

[Redshirt]

If I can tag on, Katsu is right about "hairy" Bondo for the purposes you are considering--no substitute for a job that should be done with proper fiberglass, and very difficult to sand. However, you may not have wasted your money. It does have other uses, namely external detailing. On my Spartan Laser where I had to build details up, this was great. I know my finished item will get banged around. I have a lot of corners and knife edges that I wanted beefier and to have more crack and chip resistance than regular Bondo. The "hairy" Bondo is tougher and much more chip resistant. In that limited role, it is a perfect application, but does require having a solid structure underneath it.

I do have a suggestion also on the easy sanding question. Aircraft grade Bondo is much lighter and easier to sand because it has glass micro balloons in it. Premixed, it is horribly expensive, yet the glass micro balloons themselves are cheap. Mix your own. I keep a stock on hand to mix with bondo and resin as needed. The nice thing there is that you can vary the amount of micro balloons to get the consistency/sandability you want for each application. However, adding micro balloons to the Bondo will make it slightly more brittle, further driving the requirement to have it backed by good fiberglass or other structural material.

Redshirt

 

[TheRabbit]

Anyone know of a good US supplier that will sell fiberglass cloth for cheap? Every single online place that I've found sells it for more than the cost of the 8 sqft packs of bondo cloth at Walmart. A lot of the sites I found advertise the cloth itself for cheap, like $0.50 per sqft, but then charge huge shipping/handling fees that double the price.

 

[TraumaHawk]

Do you put a light coat of resin on the outside and then inside, then put another coat on and THEN put the fiberglass mat on the inside?

 

[misfitjh]

TraumaHawk..... it depends on the method you chose to harden your stuff with and what your building. But yes you do start with a light coat of resin on the outside, myself after that I put on 2 more coats on the out side to give me a good sanding base. It helps me use less bondo. Now on the inside of a helm(depending on the helm) if you use rondo then no inside coat of resin is needed. If you fiber glass the inside then no base coat is needed as you will be putting down a coat of resin as you fiber glass.

 

[Katsu]

Anyone know of a good US supplier that will sell fiberglass cloth for cheap? Every single online place that I've found sells it for more than the cost of the 8 sqft packs of bondo cloth at Walmart. A lot of the sites I found advertise the cloth itself for cheap, like $0.50 per sqft, but then charge huge shipping/handling fees that double the price.

It depends on where you live. But 6-10$ per yard is going to be the normal price you get. It's a good price too, as a yard should be enough to do like two or three helmets:
http://www.walmart.com/ip/Fibreglas...s-Mat-8-Square-Feet/16493894?findingMethod=rr

I personally prefer the cloth over the mat, but it requires more preparation and care to use, the results are a lot cleaner and safer than mat. And TAP Plastics on the west coast sells the cloth at 6$/yard which is pretty awesome.

Do you put a light coat of resin on the outside and then inside, then put another coat on and THEN put the fiberglass mat on the inside?

You at least should have one layer of resin on the outside, and a hardening method inside (fiberglass, rondo)
Extra layers of resin inside and outside help, but are not required. Each person has their own needs and preferences, so try what works for you! It's like cures for hiccups.

My personal preference is from the outside in: bondo -> resin -> pepakura -> resin -> rondo -> fiberglass -> fiberglass -> rondo

 

[Seth Knight]

Okay, I'm planning to make my helmet in a week, so I'm checking around here and there, now I have a few questions if anyone will answer them.

1: I know the average coats of resin are two, and that your roughly supposed to wait a day between coats. Does that mean 24 hours straight (relatively), and if so what about leaving it outside? Won't the dew damage it?

2: I've heard that it's easier to sand bondo before it completely strengthens, but won't that mean it'll have the consistency of putty still? And how will that be able to sanded?

These questions may be silly, but I just want to do this right the first time. I don't have the time to mess up over and over (I want to get done before Halloween).

Seth

 

[Katsu]

When you lay resin, you want at LEAST one coat outside. The normal maximum is one out two in if you want super strength. You don't need to wait 24 hours between, I find that in the summer, two hours is enough to get you ready for the next layer. If you are doing fiberglass, a lot of people like to do the next layer while the first is dry but still sticky, so you get a better bond between the layers. The only time cold or wet really wreck the resin curing process is right away, when it's still wet, I've never had problems personally with leaving it out overnight.

It's easier to sand bondo while it's still semi putty, but it will wreck your sandpaper by gumming it up, like if you sand wet paint. I think it's better to get an oscillating sander with a detail tip, like the Black and Decker Mouse, or the Octo, as they will eat through fully dried bondo with ease and smooth the whole thing. Sanding while the bondo is half wet is gonna cost you a lot in sandpaper, but CUTTING the bondo while it's half wet is a fantastic way to prepare it! Check out Cereal's videos for good visual tips on doing this:
http://www.405th.com/showthread.php...-Chief-**-A-Step-By-Step-Tutorial-(My-Way)-**

These are not silly questions, feel free to ask more if you have them! Good luck.

 

[Seth Knight]

Thanks again Katsu (you answered one of my questions in another thread). The thread you mentioned looks helpful. I'll see if my budget allows for a power sander or not, I was planning on hand sanding it. If I have any more questions I'll be sure to post. Thanks.

 

[Seth Knight]

Sorry for a necro post, just watched the first of the videos, it was VERY HELPFUL. Thanks again for pointing me in the right direction!

 

[S0327]

Hey guys, i will be living in an apartment next year and i wont really have a ventilated spot to leave my pieces to dry after resining and fiberglassing. Is it safe for me to let it dry in like a bathroom or something? if not, how long should i wait until i bring it inside?

Thanks!

 

[misfitjh]

Def not safe to let it dry in the bathroom. Apartments are hard to work in, if you work on the balcony your neighbors complain about the smell. You can't work inside cause the smell will fill the apartment. So you might have to look into alternatives like slimcast or aqua resin for hardening. But if you do use fiber glass and resin I'd say at least a good 24hr before you bring it inside just to get rid of most of the smell

 

[Ice4Dragon]

well if it as a window and you put like a fan so that the smell go out the window instead of your ventilation.

 

[misfitjh]

I don't think that would work, when I'm working here in the garage even with the big garage door open and a fan blowing out if I open the man door between the garage and house my roommate can still smell the resin and bondo