Am i using too little epoxy resin for the fill coat?

Usually i use around 200-300 ml of resin for the fillcoat, and i feel like i sand through it really easy, so i’m not doing a good job on the sanding.
I dont do a a gloss coat after the fill coat, as i am worried it would come out bad, as i’ve done before even on burn throughs when i put some resin on them and the resin doesn’t seem to stick and spreads and it’s even harder to flatten it without going through. This is both with and without additive F.
Is my resin amount just low?
I do spread it nicely and then brush it and some even falls on the floor.
Latest board, where the goal was to do a spray paint job after. i sanded it nicely but when it got colored the imperfections popped out.

This is usually my process:
In one day:
I lam bottom, sand/push lap flush
lam top, fill coat top and lap
Next day:
cut the lap on the bottom, sand it flush
tape the edges / hard edge the tail
fill coat bottom
and then just sand up to 500grit


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The board looks good, I mean it doesn’t look awful. When you are wet sanding at 500 grit you should be able to see the surface irregularities, if you are looking with good light.

My personal approach would be to block sand the fin area a bit more, and apply another coat of resin. Its been my personal experience with epoxy that thick coats tend to be more problematic than thin coats, so I tend to go for more thin coats than less coats but thicker. If I do want to go for a thicker coat, I will typically squeegee a very thin cheater coat, and when it starts to gel, then I’ll apply the thicker coat. That’s just my approach, and I’m not a professional.

I also never finish with paint, I would probably paint the blank before glassing if I wanted that look you show, but nothing wrong with doing it your way. It just scratches a lot easier.

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Thanks for the feedback, when you say thin coats, do you brush them on while the first coat is still tacky or for what time should i aim?
I know the spraypaint would be scratchy but as this is EPS and waterbased acryl has complications as compressor and etc we went this way for this one.
I collaborated with a graffiti artist for this one, so he was most familiar with spray painting.

I will put a few coats of acrylic varnish to preserve the paint as much as possible, but it’s a surfboard anyway.

I use a foam roller for subsequent coats of resin. When the first (lam) coat is still tacky is good, but not necessary. Often I will let it harden and sand a bit if needed then do my next coat. I have never had a bonding issue regardless of time between coats, as long as the board is clean (don’t handle it with bare hands) and the surface has some tooth. Epoxy can be finicky, especially thicker coats. My point about the surface being tacky was that if I want a thicker coat, I will squeegee a very thin coat first, and then mix and apply the thick coat when it gets tacky, this minimizes problems with fish eyes or irregularities, which epoxy is notorious for.

I believe Surftech boards are finished with spray paint, but its automotive grade paint which is very durable. But still scratches, and makes matching a ding repair complicated. When you sand the repair to feather it in, you will be removing paint from the surrounding area. I have been told some ding repair shops will not work on them for this reason.

The board looks good, and if the look and the finish are acceptable to you, then thats what really matters. They all get beat up over time, cuz the ocean (and beach) is a pretty harsh environment.

Is it a special epoxy foam roller? Or any foam roller works? Can you please post a picture/screenshot of the foam rollers you use?

I’m a backyarder and not an expert but I think I saw someone much more experienced (Josh Martin?) using a spreader/squeegee to push the epoxy resin around in the hotcoat/fillcoat w/ the idea that it has a diff consistency than PE resin and benefits from diff techniques. I’ve found that (spreader) technique works for me a bit better - I start w/ the spreader and then use a brush lightly on the rails and maybe the final light passes over the top of the deck. I haven’t tried the roller but multiple people claim this is a good way to go and I have seen that used in hotcoating videos on YouTube. Second the advice about keeping the board clean and only touching w/ gloved hands. I’ve had better results w/ those techniques. Good luck!

foam roller 01
I bought some from amazon, but they sell them at Lowes too. Just a standard foam weenie roller.

I’m yet to get away with just a fill coat. I do a fairly heavy fill coat with a chip brush and sand it pretty heavily so most of it is removed and all the imperfections are sanded out, maybe a few burn throughs, then follow it with a thin finish coat. All the imperfections should be taken care of when sanding the fill coat so the finish coat goes on clean and smooth and requires minimal sanding. More steps but it keeps me from trying to fix imperfections on my final coat and burning through.

I feel like the earlier in the process you can fix the imperfections the easier the process is. Even when I roll the laps sometimes I get a ridge on the rail but if I fill it heavy and then sand it smooth it usually works. The final coat also hides all the burn throughs.

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Yes, that’s the basic idea of the hot coat (or fill coat), but sometimes I’ll do 2 fill coats with sanding in between, because epoxy can curdle or fish-eye when you put it on thick. Epoxy resin is just finicky that way, in my experience. And I prefer to hand sand, so I don’t like having to power through a thick coat, even though it’s no big deal with a power sander.

I agree that if the fill coat is sanded smooth, then the finish coat can go on very thin, almost like a layer of paint, then wet sanding & polishing to finish up goes pretty easy peazy. Also agree you need that final thin coat, for any sand-throughs with a bit of weave showing.

I wonder why the original poster was having problems with his finish coat bonding & laying flat.

Up to what grid are you sanding before applying a second coat of epoxy?
I am always hesitant to do that because i’ve got before a separation occur and also it was not a complete cover, like the resin was running away from some spots like fisheye but more, i guess that was the contamination, but any tips would be appreciated :slight_smile:

The grit I use depends on the situation, but generally 120, 150, or 220, I don’t get into the fine grits because I want a little “tooth” to bond my next coat to. If the resin is running away from spots, it must be contamination, maybe from your hands, or if you have any silicone in the shop that can be an issue. I don’t use any cleaners or solvents between coats, just wipe it clean with a dry towel, and handle it with vinyl gloves. Don’t use epoxy resin in cold damp conditions, that also can be an issue.

Some people will mix a small amount or epoxy with aerosil to get a thick paste, maybe just an ounce or two, and push that into the lamination to fill any pinholes. Then later follow that up with the regular fill/hot coat with a brush.

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Where are your sand throughs? On the laps and around the fin boxes? In your photo you can see clearly the fin box patches. I would do a “cheater” coat- brush a layer around the boxes and over the laps and then sand aggressively. You will get sand throughs at the edges of the cloth but that is to be expected. But if you get everything flat and smooth with the cheater coat then you lessen the possibility of sand throughs when you do the full fill coat. And as Huck mentioned be careful not to handle the board with bare hands

Sand those fin box patches more to even everything out. If you get sandthroughs, add a layer of 4oz even bigger over the area.
Other than that, looking good.