Read a lot of threads on this the more I read the more confused I get. Tell me it this sounds right. I can file, grind or sand the seams until they are slightly lower than the body surface; then fill them with 3M HSRF, sand that back to about surface level; then any further filler can be done with rage. Sound OK?
On a related note: at several spots by the seams there is some soft black stuff that looks like plumbers putty. Any idea what this is and how to remove it. It's too soft to sand
File or grind the seams until all of the gel coat is gone in the seams then fill with HSRF. Don't let the HSRF cure completely before you knock it down because it gets very hard. Once you have the HSRF a smidge lower than the surrounding area, fill the low areas with Rage and sand with the appropriate block until there are no more low areas. From what I have read on the forum this is not the issue that it once was assuming you have a later body such as a MKIV.
That is the way I did it and it was successful. Simplified but successful, it is very time consuming.
FFR 6055, 351W engine in 5/09, TKO 500, Pin Drive IRS, Non-donor build, Trigo 15's, Inspected and street legal 12 Oct 2011
Don't just grind out (V groove or otherwise) the parting lines for no reason. I've seen pictures and threads where guys have really cut into them when maybe it wasn't necessary. Aside from getting the parting lines flat down to the level of the surrounding body, you want the gel coat out of there as timp2 said. I see from your profile that you're building a Mk3? Some of those were pretty bad about having a lot of gel coat in the parting line area. Only remove enough material to remove the gel coat. You should see a pretty distinct clear or fiberglass color (e.g. no gel coat) at the parting lines. Some recommend using a light from the backside to make it even more obvious. My Mk3 wasn't too bad. I had a few places I had to carve out, but not everywhere. HSRF is needed only if you have deep areas to fill. Could be everywhere. Could be only in certain places as mine was. I'm starting a Mk4 build. It's supposed to be much better, but we'll see when the time comes.
Hard to say for sure, but maybe that soft black stuff is uncured gel coat? Again assuming you're working on a Mk3. Regardless, it needs to come out. You don't want to be putting your finish over it.
See the dark lines remaining after the mold flashing has been knocked down with an angle grinder and DA?
That's what you need to get rid of. If you are lucky you have a late Mk3 which for the most part did not have as much of a problem with gelcoat in the parting lines as the earlier cars. If you don't find the gelcoat stripe you can omit the HSRF and go right to Rage. For removing it on mine I used an oblong grinding bit on a Dremel to go along the line and leave a concave depression. Go Just far enough to get rid of the gelcoat stripe. Put a light under the body and it will be aesy to see when it's gone:
I taped along the areas where I needed to apply HSRF to keep the overspread to a minimum---that stuff is tough to sand. Sorry no pics of that part since I did not take many during the bodywork phase. While looking to see if I had anything that showed the HSRF application I came across a couple that reminded me of just how ugly my Mk3 body was
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