I had to fill a hole in the dash for my Truck.. So I thought I would do***ent for you all... First you want to start on the back of your repair and grind away LARGEr area than your repair.. I use 36 grit for this..... Tape front side.. Get your "MAT" rdy NOT cloth, Cloth is ONLY for finish work no strength in it at all. Rip your material DO NOT CUT ( you will thank me later)
When using this stuff.. You will also need this.. Stuff is super thick and takes a LONG time to saturate the fibers.. Now the gl*** I am using is about 1oz material this stuff.. reduce your resin 10% so it soaks in fast..
Mix your acetone resin and hardner.. I shoot a little HOT but would recommend manufacture mixing ratios for those that dont move so fast.. Wet your area first... Put down your material.. Soak your material and tap down the hairs... Let go off..
Fibergl*** cloth is Many times stronger than random fiber matte , matte is used for mainly for bulk . please , look it up . mixing resin " hot" makes for weak fiberglas . again look it up .
Hardware store resin is ok but as you note, it is really viscous, hard to saturate.. The stuff you get from the suppliers like FiberLay is much runnier, a lot lighter in color and saturates very nicely. Just higher quality. The trick to using the Bondo stuff is get a box of cheap 2" chip brushes from Harbor Freight. Use these brushes to force the resin into the mat and squeegee out excess resin and you get a good result. Problem with thinning resin with solvents like acetone is it weakens the plastic. If thinning is required, need to use styrene monomer.
Now to the front.. Prep/grind your area again 36 grit, And RIP your material small one for center a little larger for next and one to cover entire area. The black shown is NOT paint or primer it is gel coat, Coloured resin and OK to coat over.. AGain wet area and start filling hole small to largest piece..
VERY IMPORTANT HERE YOU MUST GET ALL AIR BUBBLES OUT AS SEEN ON THE EDGES ! The air bubbles show up as white or clear as seen
I need to here this explained along with witch one your call mat and witch you are calling cloth. I've been making molds and casting fibergl*** for over fourty years and disagree with one form is junk and has no strength. The woven is the strongest of the two and the chopped fibergl*** is the fastest way to get thickness on larger panels but if you put the two up side by side at the same thickness the wolven fibergl*** panel will be much stronger. I cast hoods bumpers and doors with four layers of the wolven gl*** and I used the chopped mat for the mold.
Now back to the back area.. This is where you will thank me.. As seen when you RIP your material your not creating a "HARD" edge and it finishes like the original area.. This technique applies to most Fibergl*** repairs. Even Gl*** fenders that have been cracked.. Grind the back, Put a patch let go off.. Goto front GRIND all the "white" gl*** or fractured gl*** out and fill in hole as seen filling in the hole for dash,, Grind smooth fill small pin holes and Prime..
Here is rough grind on the front.. If you work carefully it should turn out the same.. Once I sand rest of dash and Prime there will be no tell tale sign there ever was a hole there..
Again I kick my resin HOT and work FAST, Lots of years repairing boats, This was all done inless than a hour.. Including time for the resin to get hard and grinding.. One trick also, One can use Wax paper on the repair area that your are trying to fill if it has peaks and or edges, Put ALL your gl*** down cover with wax paper and use a squeegee to shape and fill your area and get air out! The wax paper will form the gl*** and hold it in place..
You are correct on this.. But same rules apply, Right amount of material and NOT resin rich. When you can see the hairs in the Mat you are about right amount, When resin sitting on top way to resin rich, Use your brush to pull out excess amount
In Havasu when I was building boats, In the summer 30cc of hardner was used, In the winter 60cc's per number 10 tin can.. YES kicking to HOT can and will compromise the integrity.. This is JUST a 101 on "REPAIR" for the back yard guy, That ONLY has access to "Bondo" brand stuff and over the counter and a supply store stuff.. Yes there is MORE Expensive materials out there that do the job better and easier... AGAIN this was for the back yard guy for small repairs NOT Body manufacturing and laying up in molds...
It'd be cool if some of you guys would at least wait until the tech thread is finished before adding your 2cents.. Thanks to the op for taking the time to share it.
Thanks for how-to ! Getting ready to maybe try some fibergl*** work to build a gauge bezel and this helps. .
(Chopped strand) mat has short bundles of fiber held together by a solvent soluble binder in a random pattern. (Woven) cloth has longer threads woven together, there is also unidirectional cloth with all fibers going one direction, except for something holding it together. The short fibers in CSM means you need to rely on the matrix (polyester or vinyl ester resin) to transfer the load from one fiber to another, this is a weakness as the strength is almost only in the fibers, the matrix itself is rather weak. The random fiber direction will give you equal strength in all directions. When the binder has dissolved after adding polyester/vinyl ester (they contain solvent, epoxy does NOT and is not used with CSM) the CSM can "stretch", to easily be worked into complicated shapes. CSM will absorb about twice it's own weight in matrix, i.e. you'll need 2 pounds of polyester to one pound of CSM. Cloth lets you design the strength by choosing the fiber directions. Cloth has bundles of full length fibers, meaning the matrix doesn't have to transfer the load between fibers in the same way. Cloth will not stretch, the fiber length is what it is, so if you need it to go into a dip in the middle of the work area, pushing the middle in will pull all of the surrounding cloth that way. Probably fine when working small pieces, a large piece of cloth covering loads of dips may have you crazy from pushing it in one dip, pulling it out of ten... Cloth can be used with polyester, vinyl ester and epoxy, the first being the weakest and the last strongest. When using hand lay up technique (just adding materials by hand, getting the air out by hand, and letting it cure in open air) cloth will absorb about it's own weight in matrix, i.e. 1 pound of matrix to 1 pound of cloth. When vacuum molding (a bit more advanced than it sounds, but basically finishing the process by placing it in a bag and **** the air out to a specific level of vacuum and **** excess matrix out, compacting the laminate) you may end up at half as much matrix as gl*** weight. Sooo... CSM is easy to work with, and most of the time good enough, especially for the DIYer. But as said, the strength mainly comes from the gl*** fibers. Using the same weight of gl*** in the three techniques mentioned above would give you products with very different thickness, weight, stiffness and strength. 1lb of hand laid CSM would need 2lb of matrix - usually polyester as it's the cheap, easy to get stuff. Total weight 3lb. 1lb of hand laid cloth would need 1lb of matrix, total 2lb. 1lb of vacuum molded cloth would have 0.5lb matrix in it, total 1.5lb. The same amount of gl***, relatively similar strength, very different weight and thickness. Speaking of the thickness that's a main factor in the stiffness, so the thickest, heaviest CSM laminate would logically be stiffer. Often a light weight core material is added between two layers of laminate to increase thickness (and therefore stiffness) but add almost no weight. Balsa wood used to be common for this, today polyurethane foam is more common. Spelling mistakes included at no extra cost. 4.32 AM and heading to bed now. Hopefully some of the text makes sense...
Thanks for this thread... answers all the questions I had for work I have coming up soon on the '27. Just curious what suppliers you guys would recommend for materials?
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