How to fix Fiberglass/resin "Air bubble" in a hard to reach spot?

[Grenex]

So I just finished putting the second coat of Fiberglass on my Iron Man helmet. I was REALLY happy with how much better I was at this coat than the first since I used 3M adhesive spray to set all the cloth in place on this coat before applying the resin. My first coat used some craft "stencil" spray which did not hold well at all...

In any case, I was all done and noticed a "weak" spot in the cheekbone area (see attached image) where the fiberglass and resin did not sit up against the paper, and is now "weak" and has flex from an air pocket between the paper layer and the fiberglass.

When I completed my first coat of Fiberglass, I notices several of these "bubbles" but I was able to fix them using my Dremel and the cutting disc to slowly remove them, refill with a thin layer of resin, and then apply my second coat of Fiberglass and resin. Apparently since this spot is in a tight and hard to see/reach places I missed it, but it now has DOUBLE resin and fiberglass on it.

I am hesitant to use the cutting disc on this since it is hard to see and I don't want to cut thru the helmet. Likewise there is not a lot of room either to work inside the helmet or to get at the proper angle. Not sure that there is another Dremel attachment I am better off using or just a better method all together to work in this tight area to fix this air pocket. I am SOOOO close to using Bondo and excited to proceed.

Any suggestions on how to work on a tight space in an angle that is impossible to see, etc.? :confused

 

[memebr]

You can drill a small hole and pour resin through it, till you fill the cavity, it will not be strong as fiber glass, but it will give some strenght to the area.

 

[Grenex]

Would I drill from the outside? How can "delicately" pour the resin?

Sent from my SCH-I535 using Tapatalk 4 Beta

 

[boshuda]

What about a dremel wand attachment with a round ball grinder?


Then maybe tape the outside of the piece and use a toothpick or syringe or something to put the resin against the tape? I'll bet if you use a q-tip you could even strengthen the resin a bit with fiber that will get left behind.

 

[Djstorm100]

I'm not follwing you boshuda...

 

[laellee]

Memebr has the right idea, drill a hole into the air pocket and fill the void with either resin or pump it full with a 2 part epoxy and let it harden (easiest). Drill from the outside, preferably through a flat surface. After you drill your access hole, blow into it to make sure that there aren't any large air leaks (resin will run out of them if you don't tape over them). If you are going to use your resin, just mix a small amount, fold a piece of paper in half (cardstock work great) and use that as a 'pour guide' to run the resin into your drill hole. You can use a toothpick or cue-tip to push more resin through the hole as well. After the void is filled up to level (or slightly under) with the drill hole, wipe any drips off the outer surface and stick a piece of tape over your drill hole. After it's cured, you'll have a reinforced void, and the hole will disappear when you skim with bondo and sand.

 

[Grenex]

Thank you Memebr and Laellee!

I actually just finished opening the area up from the inside of the helmet. Once I spent a bit more time looking at it, I realized I could gain access if I used the Dremel and the cutting disc to VERY SLOWLY cut slivers and grind edges away to expose the area that I needed. It was actually larger than I anticipated, but I was able to get a fairly clean and precise opening right down to the paper without making any cuts thru to the surface. I spent a lot of time feeling the inside/outside of the area to make sure I was cutting in the right spot and getting to my goal area.



I even identified a small area on the other cheekbone that had the same issue, and figured I would fix that too.



Now I will cut some small cloth, spray it in place with 3M adhesive and then resin it in. Hopefully I can do two coats to make it as strong as the rest of the helmet.