Gelcoat Repair Kit Supplies?

[tdonoughue]

In the same way, you can sand the whole thing with 1000 grit--it will just take you forever. If you start with the 180 grit and work downward, it will go faster because you don't have to work as much to knock down the ridges and remove the swirls as you go. That does mean you need to buy a few different grit papers, but your arm will thank you.

 

[YamaHog]

@mrcleanr6 & @tdonoughue , I wanted to check back in here and share some pictures of my repair and request some feedback. I'm very pleased with how well this went for my first attempt, however, I still have a bit of work to do I think in regards to sanding finer and re-polishing.

I got the feel of the Bauer rotary I purchased pretty quickly and polished with Meguiars M100 Mirror glaze at around 1200 - 1300 RPMs. It looks pretty good in the daylight, especially on the side of the boat under the registration numbers as well as on the suede gray above the trailer fender. However, at night with headlights hitting the side of the boat I can still see some sanding scratches. I wet sanded - 180 -> 320 -> 400 -> 600 -> 1000 -> 1500 -> 2000 on the gray, and on the white I only went up to 1500 grit before polishing. I obviously didn't remove all the scratches though. Any tips on how I should go back and sand this to ensure I remove the scratches? Any tips for seeing them better during the daylight? The ones on the side aren't noticeable except at night with the headlights hitting them. Many might consider my repair good enough, but I'm really wanting to learn how to do this properly. The pic of the rear right of boat by the swim deck was a small factory defect in the gelcoat (two tiny air bubbles) I was able to open these up a bit and fill them as well while doing the other repairs. Other than some better sanding, I'm wondering if I need to bump my RPMs up closer to 1500 on the rotary when re-polishing. So far I've only sanded and polished with 100% wool pad. I there another polish I should get for the final finishing with the black foam pad. Any tips appreciated. I'm taking my time on this repair but feel like I'm getting pretty good results so far.

 

[mrcleanr6]

i can really only see the scratches on the one where you have a light on it and those scratches look like they are from one of the coarser grits for sure. what you can do, up to about the 400 grit range is use a guide coat to be sure you have all the orange peel and scratches worked out before moving on to the next step. 600 grit and beyond, the scratches are usually too fine and guide coat wont work. a guide coat can be anything of a contrasting color with low to no film build that you can sand away and will show you where your scratches are. goto walmart or home depot and guy the cheapest matte black rattle can spray paint you can find. usually around 1 or 2 bucks a can. spray just a light mist on the gelcoat. your not painting or covering. keep the can 1-2ft away just a light mist. now sand with your 180 and you will see what you have sanded and what you havent. after 180, mist again and sand with the next grit. once all the black is gone you know your ready for the next grit...and so on. another way to guidecoat is just mix some dye, pigment or some type of solvent base paint into some acetone and wipe it on with a rag. in the boat mfg world they like to use machinists layout dye/fluid. another popular one is graphite powder. 3m makes a guidecoat which is just a tub of graphite powder and applicator pad.

 

[14SX190]

#swatski has a good repair thread and has link to prepping Post#10

https://jetboaters.net/threads/gel-coat-repair-after-snap-removal-seadek-install.19155/

I have to order a patch kit too before laying new Sea Deck.

 

[tdonoughue]

@YamaHog , congratulations! Any repair when you need to break out a special light at night and point it just right to be able to see the defect is a win in my book. Frankly, I would put down my pencil and go have a beer at this point. I think that is a great result.

That said, I understand anal (in fact, if you look it up in the dictionary, you might see my name for some subjects) and certainly understand wanting to do it right. I can't improve on @mrcleanr6 's advice (after all, he is the pro--I'm just an ameture with experience). Certainly agree those are from the courser grit. And his contrasting color idea is the same thing we do on cars with paint when rebuilding them to find dips and scratches. It works.

The thing I can offer is this: when sanding, you want to move to finer paper when you have removed all of the 'gouges' caused by the courser paper before. Then you move down again and remove the (smaller) gouges again, and so on. I think somewhere up at 320 or so you just jumped the gun and switched to the next grade before the gouges were out. No biggie.

Would love to hear if you learned anything new or anything that anyone (particularly me) said that did not work out or was wrong/not clear/different. We are all here to learn and improve, so if you have anything, be sure to post it. You won't upset me--we will all learn. Would appreciate it.

Again, a nice job on the boat!

 

[YamaHog]

we got a 73 degree day here yesterday, so yesterday afternoon I did some additional sanding on the problem areas a then re-polished. I'm now very satisfied with the result. Can see any scratches with light on the hull at night. : The advice from @tdonoughue & @mrcleanr6 was all very helpful. When I re-sanded, I just checked my sanding from various angles/lighting before moving on. I'll remember the guide coat suggestion mentioned whenever repair the lower bumper on my Camaro. I'll be working with paint rather than gelcoat for that but feel like I've gotten comfortable with my Bauer Rotary buffer working on the boat.

Things learned:

1.) Don't be scared to use a rotary buffer! Do your homework and ask others for advice as needed. @mrcleanr6 eased my mind on this earlier in this thread when he explained the different pad materials and what can get you into trouble if you are not experienced (burning paint of gelcoat). I had no trouble using Meguiar's M100 polish, a 100% wool pad, and keeping the buffer moving while working. I ended up going up to about 1400 RPMs for the final polish.

2.) Be patient and take your time on the prep work. I found the compounding/buffing/polishing to be the easiest part of my repair. The prep work is key to coming out with a good repair. Take your time wet sanding through the necessary grits to remove all sanding scratches as you go.

3.) When repairing a scuff on the left rear corner of the boat, I burned through the gelcoat to while wet sanding (gelcoat must be super thin on those corners). To build it back up using only the gelcoat paste, I brushed on a thin layer of the paste with a small paint brush. Then I hit the applied gelcoat with a hair dryer on the warm (not hot) setting. Then repeated this process for 3 or 4 thin layers. When re-wet sanding this area after it was dry, I started with 1000 grit and sanded, slowly working up to 2000 grit, taking care to not sand to much again. Then did the final polishing with the M100 & buffer, and then some by hand.

Pic after first repair a little to aggressive sanding:



Pic after the process I outlined in 3.) above:




This is the ugliest repair on the boat and I'm still very pleased with how it turned out. This area was a bI$%h to sand and polish due the curves AND the proximity to that pin stripe. Lots of masking tape was used around this area while sanding. You can see the gelcoat with built up a little higher there, but looks much better than the scrape that was there from the dock.

4.) For this type of work you will require a beverage our two. May I recommend the Yuengling Hershey Porter if you doing this type of repair in cooler weather.

Once again, thanks for everybody's input and assistance. I'm very pleased with the outcome........and if I happen to pick up another ding in the future, I'll know how to fix it now!