Sanding "Old Spot"

[Sandra H.]

Re: Sanding "Old Spot"

Thank you for the education.....

Didn't even know about the sandpaper that could become two items, but after looking at what I have, it's all wet/dry.

I want to get this right as I intend to paint it myself too.
(I wear an engraved bracelet that says "No Excuses, No Bullsh*t, No Fear" but I try not to let it get me into too much trouble.)

Thanks to all of you for your opinions, I know what I will do now and I'll let you know what happens.

Cheers, Sandy

[Jim T.]

Re: Sanding "Old Spot"

Can only add one thing to what others say about wet sanding.
Wet sanding puts paint/primer residue the on the ground or in a dipping bucket so you don't breath it.
From what I have read lead was removed from newer lacquers back when it was available so the older lacquer paint jobs would have some lead.

[Sandra H.]

Re: Sanding "Old Spot"

Jim,
Thank you for the advice.......I will take whatever necessary precautions seem right.

Not sure this will be a concern on this car....I know it was re-painted by a shop in about 1973. Don't know any details at all, but this was relayed to me by late husband's best friend.
But I'll be careful anyway.

Sandy

[Paul J.]

Re: Sanding "Old Spot"

OK, well, you're getting some idea of what I don't know about fiberglass....if polyester resin as in high build primer is what holds the fiberglass together, then what is gel? Is it also polyester resin? What's the difference between the two?

Sandy

Now you're getting to the edge of my knowledge. All of these chemistries are different. Gel coat can either be an epoxy material or an unsaturated polyester resin, similar to, but different from the polyester resin used to hold the glass fiber matrices in a fiberglass panel.

High build primer, like body filler, contains polyesters, but these materials are different from the resins in gel coat and fiberglass panels.

The polyesters cure to form crosslinked polymers, adding considerable strength.

As I said before, I'm not an expert on this, but this explanation is fairly close.

Paul

[Sandra H.]

Re: Sanding "Old Spot"

Paul,
Thanks for further education.....a couple more questions so I can make up my mind which way I want to go.

This is the scene.....I will repair the cracked fender and of course will involve body filler. Once the car is sanded, I will do further checks to see if any other places need filling.

Which one, high build primer or gelcoat, would be the best way to go over the new fender repair......and keep in mind that the car is not going to get painted for probably quite awhile.

And does the high build primer have a color to it? As in taking the place of a primer coat? My guess is that final paint would have to be applied fairly soon after this primer? Whereas I could leave gelcoat for any length of time without final paint.

My biggest goal will be to get something on the car that will protect it from further "hairy fiberglass" damage.

A lot of questions I know.....but this will give me enough info to proceed.

Sandy

[Paul J.]

Re: Sanding "Old Spot"

Sandy:

I don't do a lot of fiberglass work, so there are probably better people to ask than me, but here goes.

I grind cracks down and lay in mat. After I work this down, then I apply a couple of coats of gelcoat to seal it. I know that many people just forget about the gelcoat and use a sealer. You would probably want to use a sealer over the high build primer anyway, so it's more of a matter of choice if you wish to use gelcoat.

Primers come in several colors and you can even color gelcoat. If the car is not going to be painted for a while and it is sitting outside in the weather, I'd finish stripping the car and go ahead and prime it without doing too much finish work like block sanding. However, you can take special care to cover the car from the elements, and this should keep it from getting "fuzzier".

Paul

[Sandra H.]

Re: Sanding "Old Spot"

Paul,
I really appreciate the time you have given to this subject.....I feel like I can make my decisions now.

Considering how ratty the car is now, anything will be an improvement.

Thank you,
Sandy