New to fiberglassing questions

[lil azn 06 10+ year member]

This is my first project doing a fiberglass box install for a S2000 using Bondo resin and mat (Cheap, yes I've read up on it a long time ago but i can't convince my friend otherwise) and i have several questions. Here is a picture to begin with.

My first question is the foil acts as a an easy mold removal correct? I shouldn't have to spray it down with Pam or Vaseline or should i still?

Next, I've seen many old posts where people just make a mold of the location using resin only, pop it out, then throw fiberglass over the mold. Recently though, I've seen people have been laying down the fiberglass down first, then resin it until it makes a mold and then pop it out. Wouldn't the first choice be easier to do? Well, which way is more effective?

Thanks

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[hoxie08 5,000+ posts]

i have always put down mat and then resined it and popped it out. havent tried it the first way though so i really couldnt tell you.

 

[lil azn 06 10+ year member]

So how would i go about keeping the mat in its place when i am working above the floor? Hold a small piece of the mat and then throw resin and it will stick to the foil?

How many layers of resin/fiberglass did you apply before popping out the mold? Did you continue to add more layers once the mold was out?

Also, when fleecing, do i use a staple gun to hold its place onto to the fiberglass mold?

 

[jdc753 10+ year member]

I haven't done too much with fiberglass but have some first hand experience. The foil will work as a release but you may get some foil stuck to your resin and just have to peel it off, some pieces become more pesky than others but in the absolute worst case you could easily sand the foil out of the fiberglass.

Its a pretty large area you are working with but if you cut the mat into smaller more manageable pieces it will be easier to work with and conform to the contours. Maybe some 12x12 squares and some 4x6 squares for the tighter spaces, just general shapes though nothing exact.

I would lay down the mat and then resin over that, it might come out cleaner if you put down the resin first and then push the mat into it and then add more resin on top but I think its pretty much 6 of one half a dozen of another.

For the sides and such where you are worried about the mat not staying in place, if you hold the mat there and then dab the resin into it the mat should stay in place and allow you to work with it.

It really isn't all that hard to work with, I did my first project with it a few months back and was actually surprised at how easy it was. Make sure you work all of the air bubbles out of it by pushing them to the edges of the mat and you should be good. Not sure if you have purchased all your supplies yet but a bunch of solo cups should work good for portioning out the resin and then add the hardener to them as you are ready to use them. Have plenty of latex gloves and cheap brushes to work with, the brushes won't be salvagable after the resin hardens. I would think adding 2 layers of mat and resin and allowing it to cure should be enough for you to pull it out of the mold and then start adding more to the insides and finishing it as you need to. If this is for a sub enclosure you will probably want around 7 layers or enough till you get pretty much zero flex.

For the fleecing a staple gun should work well, I am not sure if the staples will go into the fiberglass part though, so maybe use some hot glue and tack it around as you would have with the stapler.

 

[Loud3 5,000+ posts]

I would still spray it with PAM.

 

[jdc753 10+ year member]

I would still spray it with PAM.

Yea that too, I forgot about that when I typed out my response. Will certainly make it pop out easier.

 

[bumpweLL.nYc 10+ year member]

You cant make a mold out of just resin and work off that. The resin will spill to the bottom of the well and leave nothing on the sides. Also resin works off a chemical heat reaction and if the mold is weak, the heat will warp it and it wont fit in the end.

The main objective is to layer it evenly and not have air trapped between layers (bubbles). First play with the mat only to see what size pieces you need and get 4layers torn up (by hand not scissor) and planned out. Big pieces for flat areas, small ones for curves. If you can spare the volume, cut a piece of 3/4 MDF to fit inside the well floor which would be a sufficient bottom and really cut work and material. If you choose to do just shoot some expanding foam on the well floor before the wood and let dry so it sits tight.

When you have a good handle of how its going to work out, mix up your resin in a $.99 plastic pitcher with a spout. Its the easiest way because you pour with one hand and work the brush with the other, spreading the resin and working out bubbles. Trust me its alot better than dipping the brush and dripping everywhere. Large mixes eliminate the need to count drops of hardener so you get a more even mix and critical time is not wasted. Also overstirring speeds up the reaction.

I would guess 1 liter per layer for that job. Mix it, lay it without taking sweet time with pour and spread/dab method, maybe have a buddy there to help place the mat. Wait 15-20 minutes for it to become a little tacky, mix another match, and get right back to work on the next layer using the same starting point. Its not good to let it completely harden between layers, so no goofing around! It shouldnt take more than 1 afternoon.

I would also get some 2x4's and go all the way with a false floor. How were you planning to top it off?

 

[lil azn 06 10+ year member]

I've started out the fiberglass box and ran into some problems. First off when i applied the first layer of fiberglass in pieces the floor came out fine (except for a few bubbles or bumps that need to be dremeled off) but it was hard to work in the curved areas even with small mat pieces and the result was the mat would partly hang off and dry. So then it would just bulge out. Do i just try to continue to make a mold and yank it out when ready and cut off the parts hanging off? I think one layer of fiberglass and resin should be enough to hold the form so i can take it out, dremel off the bulging parts and then put on a second and third layer.

 

[fbi90909 5,000+ posts]

you need at least 4 layers of fiberglass before you pull it out of the mold area. if you leave only 1 layer and pull it out, then begin to add aditional layers the mold can warp on you. later on when you try to stick it back in it won't sit right.

can you pist pics of what you have accomplished so far?

i don't know what technique you are using to lay your fiberglass but i will explain this one to you. you may already do it or you may not, i'm not sure but w/e. anyways you want to use a "Stippling" technique. basically what you are doing is you are stabbing resin into the mat. don't paint on the resin. what you want to do is first lay a nice thin coat of resin to the area you will be working on, this will add some adhesive, then take a peice of mat and press it onto that thin layer of resin. with a SMALL amount of resin on the brush, stab in the resin into the mat.

note: you don't want to over saturate the mat in resin. only use enough resin so the mat looks wet. not soaked.

 

[lil azn 06 10+ year member]

you need at least 4 layers of fiberglass before you pull it out of the mold area. if you leave only 1 layer and pull it out, then begin to add aditional layers the mold can warp on you. later on when you try to stick it back in it won't sit right.
can you pist pics of what you have accomplished so far?

i don't know what technique you are using to lay your fiberglass but i will explain this one to you. you may already do it or you may not, i'm not sure but w/e. anyways you want to use a "Stippling" technique. basically what you are doing is you are stabbing resin into the mat. don't paint on the resin. what you want to do is first lay a nice thin coat of resin to the area you will be working on, this will add some adhesive, then take a peice of mat and press it onto that thin layer of resin. with a SMALL amount of resin on the brush, stab in the resin into the mat.

note: you don't want to over saturate the mat in resin. only use enough resin so the mat looks wet. not soaked.

I'll post pictures later tonight, he has no compact flash reader and we are doing it at his house.

Blah, we just took out the mold, i told him to keep it in but i guess. It seems to hold its shape. Guess I'll just stick it into the trunk again. It seems to fit perfectly though.

Thanks, I'll try the stippling technique. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[pawn man 10+ year member]

1st you put masking tape over the whole area you are glassing. 2nd put down foil.(it helps if you spray the masking tape w/ spray adhesive to make the foil stick) 3rd break up mat and put it every where you are glassing. 4th mix glass and glass the area. do atleast 4 layers.

 

[lil azn 06 10+ year member]

I came back to the guys house and he decided to do another glass layer. Well, there are bubbles everywhere now.

What options do i have? Cut out all the bubbled area and reglass? Or am i stuck with rebuilding a new mold?

 

[dannyz122001 10+ year member]

as much as it would ****, i would redo it.

if i were doing a well mold, i would do the following.

after degreasing the entire wheel well, i would lay multiple layers of good masking tape. make sure to overlap the pieces and then criss-cross the next layer of tape perpendicular to the first layer, to reduce the chance of resin seeping through.

volume depending, i would cut a piece of MDF to fit the bottom (as previously mentioned). this will help add strength and rigidity to the enclosure, as MDF is stronger over flat areas compared to FG on flat areas.

next, i would spray a light mist of spray adhesive one section of the well. allow it it tack and then proceed to lay out one layer of chop mat onto the glue. this will allow you to determine the positioning of the mat before its permenant. after you are satisfied with the locations of the mat, mix your resin and apply using the previously mention stippling (sp?) method, making sure to remove all air bubbles.

moving section to section, continue until all desired areas have one layer of FG. i would recommend doing no less than 4 layers of mat. depending on woofer location, you may even want to use some small dowels as extra support to reduce warping.

once all is cured and dried, keep the enclosure in the well for about a day, again to reduce the chance of warping. once cured and removed, you can dremel down any air bubbles, knocking down any high points and further securing the MDF to the bottom (more resin and FG between the joints)

again, all FG'ing is trial and error. This method has worked for me, but to each his own. GL with it all, its pretty fun once you get the hang of it, but make sure to get all of the air bubbles out! GL!!

 

[slapmaster 10+ year member]

from the pic, i would lay a trash bag over and spray it down with something oil based. then lay presoaked matt down. the bag is easyer to release than foil. i personaly do not care if the tape, foil, or whatever i use sticks to my mold, as long as i do not make a mess or stick to trunk.

 

[lil azn 06 10+ year member]

Thanks for the advice. These guys just want to stick with this box. I've been cutting out several bubbles and plan on re-fiberglassing the areas that need to be.

I say the box in non-salvagable but he is a cheap ass and wants to stick with this box. At the rate we are going i could probably have a new mold done by tonight.

I'll never work with other people again.