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Thread: removing ripples in fibreglass

  1. #1
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    removing ripples in fibreglass

    Hi

    i have a few ripples in panels i need to remove, now my question is - what is the best way of doing this ?

    Is it - totally rub down the whole area level to the lowest point in the ripple ?

    Or is it acceptable practise to fill the 'valley' with a skim of filler ?

    thanks i advance for any input, cheers Nick.

  2. #2
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    Re: removing ripples in fibreglass

    I think your best bet is to rough up the surface and then put a skim coat of bondo on it and block sand it smooth. If you try to just sand the surface smooth to the low area you run the risk of cutting to deep and going through the gel coat into the fiberglass. Thats not a good thing. Whatever you do, don't make the mistake that I did and use your hands it just creates more ripples in the surface. Always use a sanding block and use good lighting. Light the surface from the sides not directly from above the surface your sanding or it will look good until you put paint on it. I'm not a body guy by any means and made the mistake of doing my own work in my home garage with poor lighting. Looked great, even after I primed it and sanded but once I began to put color on it my mistakes stood out like a sore thumb which cost me more time and work to correct. I learned my lesson. On my next project (Diablo) once the body it together and all parts fit tested I'm sending the body to a real body guy who's going to prep and prime the body for me at a cost of $1800.00 which to me is well worth the cost. Body work is an art when done right.

  3. #3
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    Re: removing ripples in fibreglass

    I agree with PSN in the way to approach this. Fill, block, then use a guide coat to find the "thumbs" that PSN mentioned. If you just block and sand, prime, and paint you are almost assured to find those spots. You also have to use sanding blocks of various lengths to be able to get the guide coat right. Too short of a block and you will still get the ripples.

    Mike

  4. #4
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    Re: removing ripples in fibreglass

    turmite, thanks for mentioning the various size sanding blocks I forgot about that. It does make a big difference.

  5. #5
    Senior Member MacGyver's Avatar
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    Re: removing ripples in fibreglass

    I had a metal hood a while back that was full of little dings and was very wavy. Much like the wavy fiberglass you were mentioning. After blocking it with around 80 to 100 grit, and using primer to find the low spots. I skim coated it with Evercoatís Poly Glazing Putty. Itís like a fine finish Bondo that sands very easily. After blocking it with 180 grit. And using a spray can of black lacquer to check my work I then put down a few good wet coats of primer and then blocked it once again with 320 Ė 360 grit. It was a time consuming process but the results were top notch. Having a good assortment of different blocks for the different contoured areas are also very necessary. Some of which I made myself from that pink foam insulation stuff from Home Depot. My 2 cents

  6. #6
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    Re: removing ripples in fibreglass

    SAND IN XXXXXXXXXXX'S

  7. #7

    Re: removing ripples in fibreglass

    Great advices here, you need to watch and avoid sanding the gelcoat, because if you reach the fiberglass it is all porous, and you´ll have a hard time fixing that. also using long boards will help you out, and the x pattern sanding is a great tip,

    I can tell you as my 2 cents, that you can also use UROprimer from dupont (it uses an activator and a catalyst), it is a more thick primer, that can help you give kind of volume to the panel. it also help you cover the sanding lines of the bondo more easily, avoiding the uso of plaster or putty. It works for me, if you need the exact name or product number of the primer PM me and I can take a picture of the can.

    Best regards.

    JELP

  8. #8
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    Re: removing ripples in fibreglass

    hey some really good advice here, thanks for the replies guys. I shall be following your recomendations.

    reference the long sanding blocks you make from the pink foam insulation ? In the UK maybe we dont have the same product, but in the diy stores we have the white expanded polystyrene and then lots of variations of loose fill insulation made from strands - which obviously neither would work for this application , do you know the name of the pink foam you find in the US Home Depot stores ?

    Thanks, Nick

  9. #9
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    Re: removing ripples in fibreglass

    Nick, it's just the insulation sheets that are used on the exterior of a house.

  10. #10
    Senior Member MacGyver's Avatar
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    Re: removing ripples in fibreglass

    Polystrene panel - usually comes in 4x8 foot sheets. Use a straight edge and razor blade to cut it. You can use a rubber sanding block to shape it to what ever you need for the job.

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