Teach me about seam grinding puh-lease
- Thread starter EFNFAST
- Start date
I've only once (many years ago) done a repair to gel-coat on a Corvette I owned..
I've since used epoxy primers like Eliminator and Featherfill..
I would think that if you are trying to repair the gel-coat in order to display a uniform look without paint - that you might have a tough time matching the color. Particularly if the already gel-coated panel has been exposed to UV light.
I've since used epoxy primers like Eliminator and Featherfill..
I would think that if you are trying to repair the gel-coat in order to display a uniform look without paint - that you might have a tough time matching the color. Particularly if the already gel-coated panel has been exposed to UV light.
Assuming the color you're applying is the original color used, would compounding/polishing the area remove any hazing/yellowing/oxidization that the original gelcoat has?
Alex, that is just one of the blocks you can use. Longer ones are available as well as any piece of scrap wood which is handy. You can staple the end of the paper to the end of the block if need be. Would not start at 1500 grit. Probably start around 180 and see the effects. Hard to tell without working on the piece and the amount of pressure YOU will be applying. Take note of wise Yoda's (Jac's) advice.
I would "think" so - but not having gone down that road, I could not advise either way...
The key operative here would be "original color".. How many different Gel Coat manufacturers are there and how many changes in pigment etc?
If the Gel Coating on the SLC is anything like that on my GT40, it is very thick and all the seams are proud of the surrounding surfaces.
If you really want to run it in Gel Coat - I would simply (and carefully) knock down the ridges with 400# wet on a block and then polish up from that to 1500 - all wet...
Remember though - that you should not use any wax / polish compounds or glazes on it or you may well have problems down the road when it comes time for paint...
You worry too much sometimes Alex..
Remember though - that you should not use any wax / polish compounds or glazes on it or you may well have problems down the road when it comes time for paint...
You worry too much sometimes Alex..
But you have to polish out the seams in order to remove the sanding scratches. As long as you're using a bodyshop-safe product, such as Menzerna SIP
Menzerna Super Intensive Polish PO83Q 32 oz
I don't think there should be any problems - I was talking to my painter and he re-blocks out the whole body with 220 when he does pre-prep work, so an isopropenol bath to remove any polish residue hiding somewhere, then a block sand of the whole body for pre-paint prep, will remove any hidden residue.
I may worry a lot about every single issue, but somehow my cobra has managed to stay together with 0 loose bolts/problems for the last 1200miles .... worrying about every detail is gooooood :drunk:
I meant that you seem to be worrying too much about sanding or polishing your way through the Gel-Coat...
The coating is relatively thick and if you want the car to be laser straight with perfect gaps and alignment - you will most likely need a little filler here and there ...
The coating is relatively thick and if you want the car to be laser straight with perfect gaps and alignment - you will most likely need a little filler here and there ...
Okay, so I purchased all the stuff to do gelcoat repairs (mekp, isophthalic resin, etc...). Watched the youtube videos, now had some quick questions hopefully you guys can help me out with.
Let's say you have a flat piece of fiberglass/gelcoat that is roughly 1/4'' thick. It has a hole in it that you want to repair.
Okay, so are these the rough steps? (questions are in bold)
1) On the backside, grind the area around the hole to form a good bonding area (the scarf), then clean with acetone
2) Cut out a template of the repair area on mylar, tape it on and put some object (e.g., styrafoam) against it to hold it solid in place
3) From the backside, mix your gelcoat (mine says 10drops of 1%mekp to 1oz of gelcoat), then apply ~20miles of gelcoat to the area that is being repair. Question - do I just want to do like a dozen strokes with the brush,let it dry, then move on, or do I want to do multiple layers (i.e., brush it on, wait to dry for 2-3hrs, brush on more, wait to dry 2-3hrs, then brush on a final layer)?
4) Cut out your repair area from the matt and cloth. Do 2 layers of matt, then 1 layer of cloth, then matt, cloth, matt, cloth, etc..., finishing with cloth once the area of the repair has been built up to the original area. 2 questions here
a - Between layers (e.g., matt, cloth, matt, cloth, etc...), do I want to wait for the resin to dry, or do I want to apply resin, apply matt, apply resin, apply cloth, apply resin, apply mat, etc... until it's built up, or do I want to wait, like resin, matt, wait; resin, cloth, wait. If so, how long to wait?
b - When cutting my matt and cloth templates, do I want to cut them so that initially they are the size of the hole I am repairing, then slowly get progressively bigger to expand past the repair area to cover the area of the scarf I ground above?
Let's say you have a flat piece of fiberglass/gelcoat that is roughly 1/4'' thick. It has a hole in it that you want to repair.
Okay, so are these the rough steps? (questions are in bold)
1) On the backside, grind the area around the hole to form a good bonding area (the scarf), then clean with acetone
2) Cut out a template of the repair area on mylar, tape it on and put some object (e.g., styrafoam) against it to hold it solid in place
3) From the backside, mix your gelcoat (mine says 10drops of 1%mekp to 1oz of gelcoat), then apply ~20miles of gelcoat to the area that is being repair. Question - do I just want to do like a dozen strokes with the brush,let it dry, then move on, or do I want to do multiple layers (i.e., brush it on, wait to dry for 2-3hrs, brush on more, wait to dry 2-3hrs, then brush on a final layer)?
4) Cut out your repair area from the matt and cloth. Do 2 layers of matt, then 1 layer of cloth, then matt, cloth, matt, cloth, etc..., finishing with cloth once the area of the repair has been built up to the original area. 2 questions here
a - Between layers (e.g., matt, cloth, matt, cloth, etc...), do I want to wait for the resin to dry, or do I want to apply resin, apply matt, apply resin, apply cloth, apply resin, apply mat, etc... until it's built up, or do I want to wait, like resin, matt, wait; resin, cloth, wait. If so, how long to wait?
b - When cutting my matt and cloth templates, do I want to cut them so that initially they are the size of the hole I am repairing, then slowly get progressively bigger to expand past the repair area to cover the area of the scarf I ground above?
Btw, this is the video I learned from incase my questions don't make any sense, heh
YouTube - How to Repair Fiberglass
YouTube - How to Repair Fiberglass
Oh, one more question I had (darn our inability to edit above posts!) - once the gelcoat is cured and you're going to apply your first layer of mat, do you apply the resin to just the edges of the fiberglass area, making sure to avoid contact with the gelcoat, or do you also apply resin to the gelcoat to make certain the mat grabs and sticks to it?
I'd guess the later, but then I started wondering if maybe there was some reason you wanted to avoid getting any resin on the gelcoat itself (chemical interactions, etc....).
I'd guess the later, but then I started wondering if maybe there was some reason you wanted to avoid getting any resin on the gelcoat itself (chemical interactions, etc....).