I started sanding a set of cheap Chinese fiberglass saddle bags this weekend. Two things…

- If anybody wants you to paint Tsukayu saddlebags you are in for some sanding to get them flat.

- Based on the pictures, any advice or problems that I need to watch out for?


This is my first time getting this far down into a fiberglass surface. The bags are made by Tsukayu and were shipped painted gloss black. When I got them they didn’t look bad, but if you looked close you could tell they were not flat. Now you can see how far from flat they really were.

I used a 6” Duroblock foam block and started 80 grit in a few of the worst areas. Finished with 150 on the block, and then worked all the tight spots by hand. Exposed as much a 7 layers in a couple of places and still had significant low spots left. So I am thinking this is going to take a few sessions of prime and sanding to get reasonably flat.

Thoughts?

Use some glaze where you have to. Polyester primer. Block it all out then some 2k sand and paint.

Thanks for the reply. I have lots-O-questions as this is my first time doing this.

There are a couple of minor chips and scrapes from the 5 years these have been on the bike, which do need to be filled. I don't have any experience with the polyester primer stuff. As I understand it can be tricky to get it to spray right. And if done wrong it causes more work than it's worth. With all the contours on these bags I think I would get in trouble with the slicksand type stuff. Plus I don't have a big enough tips for it.

I was figuring on 2-3 coats of high build 2K primer followed by a guide coat and copious sanding. Maybe 2 sessions of that. Followed by epoxy to lock it all down. We will see how much patience I have... directly proportional to how straight these bags get.

Any concern for the number of layers I have sanded through or the amount of build already present in the low spots?

The last layer I hit seems like resin, light green that is kind of milky clear when wet. Should I keep sanding away material until I hit the bottom of the low spots? Should I be concerned about taking too much resin off and compromising the strength of the bag? Or did I stop at about the right point? Concerns about adding millage on top of whats existing?

Judging from the photos I really think you would be Ok with slicksand. It has a higher mil thickness hold out. I'm sure you would be Ok either way even with a good 2k.

Use some glazing putty to fill your low spots prime it sand it down with some 150 and reprime. Looks to me like you did a great job prepping.

When working on plastic or fiberglass I use this for filler:
http://www.ebay.com/itm/Evercoat-Poly-F ... 3641.l6368

For cracks or damaged areas you should get cloth and resin to hold the repair together, scratch it up with some 80 grit and then apply the flexible filler.
I also use epoxy as the first round of primer since it also remains some what flexible thereby resisting cracks.

Remember the bags looked good before you started and they will look way better after you finish. These things take a beating so a good clear coat is in order.

Thanks for your input guys. New facet to my new hobby, so I can use all the help I can get. I had heard of Slicksand before, but never looked into it much until now. Didn’t even know there was a difference between body filler and glaze until this came up.

Slicksand… Sounds like good stuff. I can definitely see where it would be great for large areas. But I don’t think this is the project for me to start playing with it.

Glaze… Looks like the way I am going. Seems much more suited to what I’m trying to do, controllable for small areas where minimal build is needed. I’ve done a lot of drywall, so this should be somewhat of a familiar process.

Went to NAPA yesterday afternoon, they have a Sherwin Williams shop inside the NAPA store. Apparently the paint guy was skimming and got fired. $35,000 worth of product missing since Jan. 1st. Too bad because he always had answers.

The parts guy looked at me like I had two heads when I told him what I was trying to do. He called his boss over, but she didn’t know much either. They did have the Evercoat stuff you linked, 30oz. for $75!!! They also had a few other lower quantity, lower cost options which would probably work fine. But the team at NAPA was completely clueless. They didn’t even know if the stuff needed hardener. Without someone knowledgeable saying it’s going to stick and stay stuck I am hesitant to use it.

I’m going to hit Finshmaster this afternoon and see what they have.

Yeah, you need a "real" paint jobber for your supplies. My nearest PPG supplier carries just about every brand of filler you can get. I pay $25 for a 24 ounce squeeze tube of USC's Body Icing which is an excellent poly putty for what you are trying to do here. And, just further, don't let Slicksand scare you... trust me, the stuff is just literally sprayable bondo. The only thing you have to watch is your "time" to make sure it doesn't harden in the gun. Spraying it with a 1.8 tip or larger is best and the bigger the better up to say a 2.2.

Went to Finshmaster and got some pourable putty. Easy enough to work with. Gets hard fast using the recommended amount of hardener. Cut back a little and it worked better.

Every time I thought I had something flat I would sand and find there were still low spots. I gave up after 6-7 tries and said that’s close enough and laid the first coat of primer. Yeah, I’m just going to have to live with some minor imperfections. No one else will ever know they are there.

This is the second coat of primer. There is a faint halo around where I sanded down into the fiberglass. Should I be concerned? Or should I just lightly hand sand and move on to epoxy?

thats just your solvents eating your feather edge. cut it down doing your best not to burn through and reprime one more time.

Blew up your pic......looking pretty good. Trust me, foreign fiberglass....none of it is flat or straight.....