So long story short by bumper got crunched yesterday so i gotta fix it again.
generally what you need: fiberglass mat, resin w/catalyst, chip brushes, graduated mixing cup, latex/nitrile gloves, scissors/shears, painters tape, bondo, and a cleaner such as mineral spirits, a wire brush, and some paper towels/shop towels.
first assess the damage:
not too bad, since i'm not missing any pieces it will go back together quite nicely.
yeah metal needs work too but ill do that later.
first thing i did was use the wire brush to lightly pick/scrape any excess/loose pieces of glass off. Then I used it to scuff the inside and outside of the bumper on the areas to be glassed back together.
Use the painters tape (2" wide if you can, works best) to hold the pieces together. this to me is the most important step. if you do it properly and made everything line up the best you can, without high or low spots, it saves your lungs during sanding later.
anyway, after doing that clean and prep the inside surface by scuffing with the brush as stated and then using the cleaner to get any loose debris/dirt/glass out. use paper towels to wipe it down and allow to dry. you can use water but cleaners that are more volatile will dry much faster than water. Also due to water's polarity, it won't take things like oil off as oil is nonpolar.
After allowing to dry your almost ready to glass.. So the best way to approach this is see where you need the glass the most. Cut some strips to cover up the crack in the glass to bond the 2 pieces back together. Lay the piece over the glass and make sure its going to work ok. heres what im shooting for in terms of coverage:
Get your graduated mixing cup and determine (estimate, and its better to mix more than less resin!) how much resin you will need. to cover an area of about 2-3 sq ft i'd say used about 4 oz resin. the resin requires the catalyst to kick off so you can take your time pouring the resin. when ou get a good amount, get your catalyst and start adding drops corresponding to the resin. (USUALLY about 12 drops per oz of resin). do this quickly, and as soon as you have the drops in, get your chip brush and start mixing them together WELL.
start laying the resin down where you wish to put the fiberglass in a thin coat, just to adhere the glass to. Lay the glass down 1 strip thick at a time. if you put down more than 1 strip thick, it gets tough to work with and just globs up into a mess. It is important to try to avoid getting any air pockets. The best way to do this is to take the brush and rather than stroke, you want to blot the fiberglass down. The brush will be ruined anyway so apply good pressure even if you bend the bristles and whatnot.
Aim for this:
no air pockets, bubbles, nice and flat. i'm still learning on this so i'm not the best at it yet.
This is what you want to avoid:
i screwed up here and ran out of resin so i didnt get enough and thought i could leave some fiberglass there. wrong, what happened was SOME resin got on it and lifted it up so i coudlnt get it to lay flat on the next pass. i ended up cutting that part out and redoing that layer. just makes for a mess though.
Continue with this until you feel satisfied with the coat. Do one even coat of 1 strip thick glass at a time and this will let everything adhere well with no air pockets. Seth told me to put the brush into the cup with the remaining resin as it makes it much easier to clean up later. This way you can pull the resin and brush out as one piece, and save yourself the hassle of scraping the cup out.
Anyway I have some more pictures of the steps and I will edit this and upload them as I go. Probably wont get to bondo today but i jst wanted to get some structure back to the bumper.
