gel coat paste repair

[findinghomer]

i filled a couple gouges with spectrum color gel paste. final results turned out pretty good, got a nice fill with smooth flush , and shiny finish. but i can see a slightly dark outline of the exact repaired spot. what did i do wrong and how can i fix this? here is what i did....


applied gel into gouge and over
once dried i sanded with 220 grit
once flush i wet sanded with 400 grit
then again wet sanded with 600 grit
then wet with 2000 grit
then applied some scratch polish then wax.


anyone got any tips?thanks

btw boat is white.

 

[BWT]

Re: gel coat paste repair

it's called a halo. I am guessing that before you laid the gel in you may have forgotten to lightly sand the surface (1000 grit or so, larger than the repair area) to remove the oxidation/staining around the repair area(s). By skipping this step and laying in the new gel, when you sand it flush, you're left with a ring (or halo) of the old gel around the new on the feathered edge (just under the surface where it's thin enough to be somewhat transparent; that's why you can't sand it off). If you sand first, you'll be rid of the halo, but will have a bulls-eye with the new patch until it oxidizes and blends with the surrounding old (original) gel. If you decide to re-do it, the repair are will be larger in size; so if the gel color isn't spot on, it will appear more obvious;it's a trade off.

Hope this helps
~BWT

 

[findinghomer]

Re: gel coat paste repair

will oxidation hide it at all?

 

[findinghomer]

Re: gel coat paste repair

thanks BW your right , i didn sand the original damage first... when i mixed the gel coat i had to mix half the 2oz bottle, as they recomend. so i had a bunch of extra gel, so i went around and filled any little gouge i found. obv i did them all the same, no sanding prior. but all the other ones i haven finished yet, is there anything i can do at this point when i begin to finish the others to minimize the haloing? thanks alot for your help ill def remember to do that next time.

 

[findinghomer]

Re: gel coat paste repair

is it possible to sand theses areas down with 150 and add liquid gel coat or a paint and resand?

 

[BWT]

Re: gel coat paste repair

if you have a colored gel (not paste), then you can sand the area around each spot with 1000 grit to clean, then sand only the repair spot with 120 (get it good; need to feel a little dimple over the fill spot) clean with acetone and either spray or brush on the gel. For this kind of thing I would use regular laminating gel and when it's tacked mostly cured but still feels a little sticky) go over with a light coat of PVA to fully cure the gel. block sand starting with 600 until mostly flush with the surrounding surface and start working through the numbers (1000 grit, and finish with 1500). depending on the year and make of the boat, you might be able to get a color match from Spectrum color, otherwise contact a marina to see if they have someone that can mix the gel, or if you're up for a challenge try it yourself Let me know how it goes!

 

[findinghomer]

Re: gel coat paste repair

thanks bw, i was hoping that was possible. the gel coat is just white, the paste patch kit i bought before was spectrum factory color match, kind of brighter but i assumed bc i removed alot of oxidation. bc its white and the paste kit was so expensive i went ahead and just bought a west marine white gel since you get more for alot less. if its not a perfect match i wont be too disappointed . thanks alot for your help

 

[BWT]

Re: gel coat paste repair

one thing I didn't mention which I am sure you are aware of is that the gel needs to be catalyzed with MEK-P; roughly 12-15 drops per ounce of gelcoat. It's better to lay up a little too much and sand off than not enough and be dealing with skim coats to make it look right. In order to properly cure gel needs to me roughly 20 mils thick (little less than 1/16"); otherwise it doesn't fully cure. Depending on the location and application that may not be super critical. As long as you can work the repair without it clogging the sandpaper you should be fine. Good luck!~

~BWT