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 Post subject: Bondo vs. PC-7
PostPosted: Wed Jan 24, 2007 7:50 am 
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Which is stronger? Bondo or PC-7, or are they about equivalent?

Also, do you find that they have the same consistency?

Finally, is there a 'resisit' that one can use to inhibit Bondo from sticking? PC-7 doesn't appear to stick to wet surfaces, so I'm wondering if Bondo might behave simiarly.

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 Post subject:
PostPosted: Thu Jan 25, 2007 12:14 am 
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Hi CS...I really can't help you with the pc-7 as I have not used it yet, but bondo by itself is really not that strong. It will adhear to just about anything and even more so to objects of similar make up.

Now adhesion and bonding are to very different matters. Bondo will adhere to plastic for instance but it will not bond with it. If you flex the plastic to much the bondo will separate.

You can buy bondo that has strands of fiberglass within and it is much stronger. Moisture effects how the bondo sets up. I've never tried a wet surface but I believe the moisture would create an adhesion barrier. The bondo would set up but not stick to your part.

Not to be nosy but in regards to the strength issue can you give an idea of how the strength has to be applied?

Hope this gives you a little info :chase

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 Post subject:
PostPosted: Thu Jan 25, 2007 1:45 am 
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Interesting. I'm dealing with a Golden Armor helmet which I thought would be identical in shape with the Don Post Deluxe. Despite the popular belief that the Don Post Classic Action being cast from the same mold as the Deluxe, it apparently isn't true. There are various differences that cannot be attributed to mold degredation or simple distortion.

Anyways, the helmet's flange is too short. I've seen tutorials of people using bondo to extend the flange by a few inches, and I am wondering if I should do that.

One idea is to use the dremel to create some "T"-shaped holes into the flange for the bondo to grip into, so there is more surface area other than just trying to adhere it to the end.

Then another thought was to use PC Plumbing Epoxy. In my initial modification of my Rubie's eyes, I found it to be incredibly strong, almost tougher than the plastic itself. Well on the Golden Armor fiberglass and resin (with the resin being a bit chalky) my only concern is that it becomes harder to sand than the fiberglass itself.

I'll have to experiment a little.

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 Post subject:
PostPosted: Thu Jan 25, 2007 2:16 am 
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I did some research on PC-7's website, and it seems that people use it to bond things and it can support incredible weight. I'll give PC-7 a shot.

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 Post subject:
PostPosted: Thu Jan 25, 2007 9:22 pm 
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Well I called up PC-Epoxy regarding PC-7 and it sounds like PC-7 is very friendly with fiberglass, and contains a substance that allows it some flexibility. They believe that bondo -- over time -- may separate from fiberglass.

They've used PC-7 to mount those holders on artificial rock climbing walls, so if it can hold that much weight it should be fine.

I will try my dome extension with PC-7. The downside is that being so cold here in CA (45 degrees today) the PC-7 (which requires 70F) is simply not going to cure overnight and may need the assistance of a heat gun.

But it's been a lot easier work with. Equal parts of this goop and that goop give you what you want. You don't have to worry about "did I use enough hardener).

While I used water and wet my hands to spread it more smoothly, they suggested denatured alcohol. They did warn that one in a thousand people have an adverse reaction with water and PC-7.

I'm also going to use my Dremel disc tool to cut angled grooves into the rim of the flange to increase the surface area the PC-7 will be coming into contact with -- and to fill. In this way it's more than just adhering to the end of the flange but integrating with the structure.

By the way, I'm not lengthening the flange just for the sake of lengthening it. The helmet of the fiberglass Don Post Classic Action recast kit I received is actually shorter than the helmet of my original Don Post Deluxe, if that were possible. I'm basically going to restore it to its proper length. I'm not an advocate of lengthening the flange just to cover the back of the neck without first trying to simply reangle and reposition the helmet.

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 Post subject:
PostPosted: Fri Jan 26, 2007 12:32 am 
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I've heard alot of good things about pc-7. Almost picked some up today but could only find pint size cans, would like to find quart size ( if they make them ) to have enough for more than one project at a time.

Bondo would not work for long for what you plan, if you got it to work at all so good call on the pc-7.

I wish you luck.

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 Post subject:
PostPosted: Fri Jan 26, 2007 1:19 am 
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T-VIRUS wrote:
I've heard alot of good things about pc-7. Almost picked some up today but could only find pint size cans, would like to find quart size ( if they make them ) to have enough for more than one project at a time.

Bondo would not work for long for what you plan, if you got it to work at all so good call on the pc-7.

I wish you luck.


After doing a bunch of research on other people's tutorials and recommendations and then not getting the results I intended, I'm now having to research the research -- qualifying why people say "use this" or "don't do that".

I believe thet pint size cans are actually available off of their website. Home Depot didn't seem to carry the cans either. They get expensive but a half gallon is cheaper and will probably last me for more than a year, unless I decide to sculpt a whole original something out of PC-7!

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 Post subject:
PostPosted: Fri Jan 26, 2007 1:27 am 
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Hi CS...One question I have for you since you use pc-7 is can it be molded into a shape before it sets up? What I meen is could it be used to form the extra neck and flare on say....darth ugly? I don't know how workable it is.

And please don't take my info on bondo as gospel, I'm by no means an authority. These are just my observations from using it over the years at the body shop, and in my work shop at home. :chase

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 Post subject:
PostPosted: Fri Jan 26, 2007 1:43 am 
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T-VIRUS wrote:
Hi CS...One question I have for you since you use pc-7 is can it be molded into a shape before it sets up? What I meen is could it be used to form the extra neck and flare on say....darth ugly? I don't know how workable it is.



I've only used it to reinforce the interior of a Rubie's helmet where it's already leaning up against something rigid. I don't know how it will behave just standing alone. You may have to do this in increments if you do not want your application to sag under its own weight.

As opposed to QuikPlastic which has a working time of about 12-15 minutes before it hardens (which, if it does, you can sometimes soften it back up before it cures by using a heat gun), PC-7 has a working time of about an hour, which is definitely useful for patient people but not for impatient people.

The working method is different from a putty. It is categorically a paste, so it's not going to behave like a clay at all until it partly cures.

Also, you really have to watch your curing temperature. They recommend a minumum of 70F and I don't blame them. It's taken 3-4 days even under sunlight for my application to cure because of the blasted cold here, and today it's been 45F.

When it's semi-cured it will start responding a bit more like a clay.

I've not tried this yet, but in theory what you may need to do is get a rigid enough plastic sheet, tape it in place, and wet it (or use denatured alcohol) and apply the paste against that. I've been at Home Depot and found some 3" wide rubber strips. These are to line kitchen walls where the wall meets the floor. They look stiff but they are amazingly flexible and hold their shape pretty well without a heat gun.

So assuming you have a good working temperature, you might be able to just simply put a bunch of putty to extend the neck and let it sit. It can be a rough job. After you've let it cure for 15 minutes, test it to see if it's still pasty. If it is, try again another 5, 10 or 15 minutes later. Again, you have up to an hour. Don't sand it at this point because it's still semi-goopey. If you want to shape it, press it. Wet a soft plastic spreader and press into the application. Even if you don't get your application looking perfect, there's always the sanding option later.

If it holds up under its own weight, and seems to behave more like a clay, then remember the time and approximate thickness and develop a "feel" for how it behaves.

By the way, your avatar isn't showing.

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 Post subject:
PostPosted: Fri Jan 26, 2007 2:16 am 
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Hey thats a great idea about the molding...I never thought of that the flooring guys have tones of it right now on my job. Hmm...maybe tomorrow I'll steal....I mean ask if I can have some and try it this weekend I'll let you know how it works. Thanks.

How do I know if the avatar isn't showing...I can see it on my computer?

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 Post subject:
PostPosted: Fri Jan 26, 2007 2:29 am 
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T-VIRUS wrote:
Hey thats a great idea about the molding...I never thought of that the flooring guys have tones of it right now on my job. Hmm...maybe tomorrow I'll steal....I mean ask if I can have some and try it this weekend I'll let you know how it works. Thanks.

How do I know if the avatar isn't showing...I can see it on my computer?


Regarding your avatar, it may be depedent on your cookied login to the file service you have access to. Those of us not logged into that service don't have access. Do try photobucket.com instead.

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 Post subject:
PostPosted: Thu Feb 08, 2007 7:43 am 
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Okay, guys, I've tried PC-7. At first I thought it was a good idea that it doesn't stick to damp hands, so the instant I put latex gloves on, I'd dab them in water and proceed to mix equal parts of "A" and "B" and spread them.

I was doing more than just filling cracks. I was building structure. In other words, a projedt that involves a Don Post Classic Action recast, I had to saw off the three mounting prongs on the head, and I attempted to use PC-7 to rebuild the missing areas so that the skull cap was seamless.

I had left it for days to cure, and exposed to sunlight. The curing temperature is 70 degrees and unfortunately the weather around here has just recently gotten a wee bit better but it's still below 70.

Today, I tried to test the bonding strength and it pretty much failed. It broke. It also was a pain to sand and gunks up the sandpaper. It always had a slight softness to it, and resembled a clay that still seeped some kind of oil.

Now here is a disclaimer. I have used water as a resist to my hands. It has also been cold. Moreover, my applications are at least 3/8ths of an inch thick. I'll give PC-7 the benefit of the doubt that it didn't cure properly.

Covnersely, I've tried PC-11. PC-11 is their "marine" version and mixes white. It can harden under water which means you had better use latex gloves because it may not come off your hands! PC-11 seemed far more compatable with the resin. In areas where I started building structure to the resin, it won't break off. It sands well like the resin as if it were a part of it.

The downside is that it's incredibly sticky and gets everywhere which means you have to be very carefull. If you're into lengthening flanges, PC-11 may be your choice if you want to use the PC brands. For facemask work, I'd use something else. I've just scraped off, filed off and sanded off the remnants of the PC-7 I was using to build out the skullcap out of my DP CA facemask. Later this week I'll use PC-11.

Again due to the temperatures here, I may have botched PC-7.

Thus far I have not had positive experiences with PC-7 to recommend it as an alternative to bondo. I'm hoping that someone out there can prove me wrong regarding PC-7 (just try to adhere to an important part of the mask and try to break it off).

I may try Bondo later..

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 Post subject:
PostPosted: Fri Feb 09, 2007 12:30 am 
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Hi CS. Bummer about the pc-7...I have not picked up any yet to try so can't help out yet. Might get some this weekend but temps here have been in the -10 range as of late and with my work room in my basement its only around 60 down there. Not sure I should try it till it warms up..

To raise the temp to 70 or 75 in the room it raises the temp upstairs to about 90...this does not go well with the wife. :rolleyes

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 Post subject:
PostPosted: Wed Feb 14, 2007 10:10 pm 
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I'm now going to begin recommending PC-11 (extremely sticky paste) and the more easily working putty AquaMend.

My review of the two are at:

http://www.aokforums.com/thepropden/the ... .html#5146

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 Post subject:
PostPosted: Tue Apr 17, 2007 9:17 pm 
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I've had some limited experience with Bondo on two separate helmets from two separate people, and I'm finding that Bondo has been somewhat brittle in these cases. I'm not sure if too much hardener was added in each separate case, but I've now come to find Aquamend to be very difficult to break.

A while back I dropped a Golden Armor helmet, and the resin broke but the Aquamend stayed strong. Amazing.

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