The more I sand the worse it gets

[Jeff's First FFR]

Hi all,
Hope you all are doing well.
In my continuing saga of sanding the parting lines it seems that the more I uncover the worse it gets. The surfaces adjacent to the parting lines are not in the same plane. I have been sanding and grinding to make them smooth. However, I have uncovered many holes (bubbles in hte resin) and voids. I hope I am doing the right thing. The surfaces are very uneven and it is difficult to get hte gel coat out of the gaps in the parting lines. Here are some photos.

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I will fill these holes and voids with HSRF. Then sand more. Is that correct?
Please comment if you can.

Thanks,
Jeff

[Jeff's First FFR]

Hi all,
Hope you all are doing well.
In my continuing saga of sanding the parting lines it seems that the more I uncover the worse it gets. The surfaces adjacent to the parting lines are not in the same plane. I have been sanding and grinding to make them smooth. However, I have uncovered many holes (bubbles in hte resin) and voids. I hope I am doing the right thing. The surfaces are very uneven and it is difficult to get hte gel coat out of the gaps in the parting lines. Here are some photos.

142391
142392
142393
142394

I will fill these holes and voids with HSRF. Then sand more. Is that correct?
Please comment if you can.

Thanks,
Jeff

Just me again. Yes there is clay in the voids. Why did they use RED clay? Looks same as gel coat. Anyway... on with the process.

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[Jeff Kleiner]

Stop sanding! You're taking too much gelcoat off which is opening up hundreds of pinholes in the glass that will haunt you.

Not withstanding mold shift that results in unevenness in adjacent surfaces (we'll get to that in a minute) you just want to take the mold flash down to flush. Here's a typical one after spending about 45 minutes with 40 and then 80 grit on a DA. You'll see that there isn't a large amount of raw gray fiberglass showing:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142404&d=1532310142

You don't need or want to open up any more raw glass than necessary but the gelcoat does need to be well roughed with 80 anywhere you're going to apply filler---you must have the mechanical "tooth" because it won't adhere to slick gelcoat.

As for the mold misalignment it's not uncommon to have a "step" similar to this:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142407&d=1612974724

You don't deal with this by only taking the high side down because you can end up getting thin and also when doing so you're widening the line and exposing more raw glass. It's best to kind of split the difference by taking the high side down conservatively and bringing the low side up with filler (Note that after this photo was taken the still shiny gelcoat nest to the edge was sanded and scuffed). You'll wind up with some wider areas of filler to get the contours to flow smoothly. The one in this photo had misalignment all the way around but most times it'll just be one corner or the nose. Luck of the draw...

https://thefactoryfiveforum.com/attachment.php?attachmentid=142408&d=1612975335

You mentioned voids although I don't see any in your photos. If you find voids along the parting lines like these they'll need attention:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142409&d=1612975675

I address those by running down the line with a round or oval cutter in a die grinder to create a radiused trench which is then filled with HSRF:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142410&d=1612975941

Fill only to flush because you REALLY don't want to have to sand any more of this rock hard stuff than you absolutely have to! With that done you can then start doing your shaping with Rage Gold or your filler of choice.

Hope some of that helps and good luck!

Jeff






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[rich grsc]

Oh come on Jeff, lets use HSRF for the whole car. Really important to let it cure for at least 48hrs.:rolleyes:

[Jeff's First FFR]

Stop sanding! You're taking too much gelcoat off which is opening up hundreds of pinholes in the glass that will haunt you.

Not withstanding mold shift that results in unevenness in adjacent surfaces (we'll get to that in a minute) you just want to take the mold flash down to flush. Here's a typical one after spending about 45 minutes with 40 and then 80 grit on a DA. You'll see that there isn't a large amount of raw gray fiberglass showing:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142404&d=1532310142

You don't need or want to open up any more raw glass than necessary but the gelcoat does need to be well roughed with 80 anywhere you're going to apply filler---you must have the mechanical "tooth" because it won't adhere to slick gelcoat.

As for the mold misalignment it's not uncommon to have a "step" similar to this:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142407&d=1612974724

You don't deal with this by only taking the high side down because you can end up getting thin and also when doing so you're widening the line and exposing more raw glass. It's best to kind of split the difference by taking the high side down conservatively and bringing the low side up with filler (Note that after this photo was taken the still shiny gelcoat nest to the edge was sanded and scuffed). You'll wind up with some wider areas of filler to get the contours to flow smoothly. The one in this photo had misalignment all the way around but most times it'll just be one corner or the nose. Luck of the draw...

https://thefactoryfiveforum.com/attachment.php?attachmentid=142408&d=1612975335

You mentioned voids although I don't see any in your photos. If you find voids along the parting lines like these they'll need attention:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142409&d=1612975675

I address those by running down the line with a round or oval cutter in a die grinder to create a radiused trench which is then filled with HSRF:

https://thefactoryfiveforum.com/attachment.php?attachmentid=142410&d=1612975941

Fill only to flush because you REALLY don't want to have to sand any more of this rock hard stuff than you absolutely have to! With that done you can then start doing your shaping with Rage Gold or your filler of choice.

Hope some of that helps and good luck!

Jeff


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Looks like I went too far. I thought I had to remove ALL the gel coat. Lesson learned.
Thank you Jeff

[juddster]

Great information. Thank you for the questions and answers.

[Jeff's First FFR]

Yeah, Jeff, you are right...that stuff is hard. Six 40 grit DA disks later...
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Good thing I'm not building a SHOW car.
Now...what was the name of that RED RUST-O-LEUM?

[David Hodgkins]

Glad you've got it back under control!

:)

[Jeff's First FFR]

Glad you've got it back under control!

:)

Thank you...panic for awhile. I guess that will hold it until I can save up enough of my Social Security to have it done professionally.

Jeff

[Norm B]

If you’re not aiming for a show car then don’t give up. I did my own and it looks OK and nobody notices the flaws I know are there. As you have already seen, the experts on the forum are great and will offer advice if you ask. Take your time, work on one area at a time and save your bad words for fitting the driver’s door.

Norm