The SB Assassin
New Member
Working on an Iron Man suit and it's almost all fiberglassed, so I'm looking at the next step of applying Bondo to the pieces. Just wondering if there is really a difference between regular Bondo and fiberglass Bondo.
Is there really a difference between regular Bondo and fiberglass reinforced Bondo?
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Re: Is there really a difference between regular Bondo and fiberglass reinforced Bond
Yes, big difference. Fiberglass-reinforced bondo (whether with short-strand or finer additives) is quite a bit stronger, but it is also A LOT harder to sand. I don't use it on any pep stuff for exterior smoothing, it's not worth the sanding headache. Regular bondo can still be quite a bit of work to sand down; you can get featherlight types that detail and sand more easily, but they won't really add any structural strength. I Just lay 2-3 layers of fiberglass matt and resin on my pieces, then finish with featherlight on the exterior.
Yes, big difference. Fiberglass-reinforced bondo (whether with short-strand or finer additives) is quite a bit stronger, but it is also A LOT harder to sand. I don't use it on any pep stuff for exterior smoothing, it's not worth the sanding headache. Regular bondo can still be quite a bit of work to sand down; you can get featherlight types that detail and sand more easily, but they won't really add any structural strength. I Just lay 2-3 layers of fiberglass matt and resin on my pieces, then finish with featherlight on the exterior.
The SB Assassin
New Member
Re: Is there really a difference between regular Bondo and fiberglass reinforced Bond
Every piece has been pepakura so far, but I'm putting the fiberglass on the inside and the Bondo on the outside. I'm not looking into going out and fighting crime after I finish this suit, I just want it to be durable. From your reply it sounds like you put fiberglass on the outside.
Every piece has been pepakura so far, but I'm putting the fiberglass on the inside and the Bondo on the outside. I'm not looking into going out and fighting crime after I finish this suit, I just want it to be durable. From your reply it sounds like you put fiberglass on the outside.
Re: Is there really a difference between regular Bondo and fiberglass reinforced Bond
Nope, inside. I resin outside once to stiffen the paper, then resin and glass in usually 2-3 layers on the inside to get the piece more rigid (some people do 1-2, it's a weight vs strength trade-off, personal preference). After that, I start bondoing/sanding/priming/repeat on the exterior until it's where I want it. So all the mat is on the inside, just a resin base and bondo on the outside. That's what I do anyways.
Nope, inside. I resin outside once to stiffen the paper, then resin and glass in usually 2-3 layers on the inside to get the piece more rigid (some people do 1-2, it's a weight vs strength trade-off, personal preference). After that, I start bondoing/sanding/priming/repeat on the exterior until it's where I want it. So all the mat is on the inside, just a resin base and bondo on the outside. That's what I do anyways.
The SB Assassin
New Member
Re: Is there really a difference between regular Bondo and fiberglass reinforced Bond
Do you use a pepakura file for the helmet?
because I'm wondering if the edges of the faceplate are gonna be an issue after I apply the Bondo
Do you use a pepakura file for the helmet?
because I'm wondering if the edges of the faceplate are gonna be an issue after I apply the Bondo
Re: Is there really a difference between regular Bondo and fiberglass reinforced Bond
That's where clean pepakura building can really make a difference. I resin the faceplate and other components in their correct places at the same time, and then separate them again. While separated, I resin the edges and lips that got missed on the individual pieces, let them cure, and then tape or hot-glue them back together temporarily for the bondo application. Applying the bondo and sanding with the pieces helps with the parallel surfaces and symmetry. You'll still have to apply bondo and sand out the meeting edges after the majority of the surfaces are done.
As for the edges that get bondo application, you can sand them sharp with a flexible block/etc... The thinner the bondo coats, the better. Edges that are bondo'd can still chip, but they are pretty durable, especially once primed and painted.
That's where clean pepakura building can really make a difference. I resin the faceplate and other components in their correct places at the same time, and then separate them again. While separated, I resin the edges and lips that got missed on the individual pieces, let them cure, and then tape or hot-glue them back together temporarily for the bondo application. Applying the bondo and sanding with the pieces helps with the parallel surfaces and symmetry. You'll still have to apply bondo and sand out the meeting edges after the majority of the surfaces are done.
As for the edges that get bondo application, you can sand them sharp with a flexible block/etc... The thinner the bondo coats, the better. Edges that are bondo'd can still chip, but they are pretty durable, especially once primed and painted.
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