HOW TO SAND A SURFBOARD

1. Will sand jobs become easier with a multi speed power sander? I only done it by hand and it seems impossible to not burn thru plus it takes a lot of time.

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2. I layed a hot coat and am sanding with the 120 grit. I'm finding excess resin in drips and bumps that are very hard to blend out. any suggestions?

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3. I glassed with epoxy resin, when the hot coat is set, and say if I want to sand out any imperfections before the gloss coat, what grit would you recommend starting at and going up to? And would you just use a random orbital sander for this?

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4. What's the best way to sand a double concave hotcoat? I have a medium and soft 8 inch Flexpad but I'm not getting the deep part of the concave. Can I use the soft pad with 150 grit to get rid of the shinies?

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5. I sanded through the hotcoat in some spots and can see the fiberglass weave. My question is do I simply coat the spots with weave exposed and then re sand? If so what grit should I start sanding with ?

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6. How do I sand the gloss coat to eliminate scratches and make it shiny?

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7. Took some 80 grit to my hot coat and I can see where I burned through. If I'm going to do another hot coat, do I continue to sand so all the marks come off from the 80 grit or do I just do my next hot coat?

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8. How to I grind the lip of a 10.5 centerfin box down?

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9. What is the difference between sanding and 'grinding'?

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10. My FCS X-2 plugs are melting when sanding them down

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11. Velcro face sanding pads or cloth face Flexpads better for sanding?

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12. I have a lot of really tiny air bubbles that are filling up with dust during sanding and making my tint job look bad

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1. Will sand jobs become easier with a multi speed power sander? I only done it by hand and it seems impossible to not burn thru plus it takes a lot of time.

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A power sander will increase the speed and ease of your sanding but will require some practice to get used to it. Selecting the right Flexpad Sanding Pad for the job will help you sand efficiently and minimize burning through the hotcoat into the fiberglass (which that area would need to be re-hotcoated and sanded again).

Hard Flexpad for flat areas and grinding down finboxes
Medium Flexpad - good all around sanding pad and we recommend if you're going to buy one Flexpad, the Medium density is the best one to get to start. It will sand the entire board well but not perfectly.
Soft Flexpad - Great for higher grit sanding (220+ grit) of the hotcoat and also your surfboard rails. 

2. I layed a hot coat and am sanding with the 120 grit. I'm finding excess resin in drips and bumps that are very hard to blend out. any suggestions?

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Try sanding with a more aggressive sand paper like 80 grit on Hard Flexpad until it is blended. 

The goal of sanding is to get all the resin flat and level.

3. I glassed with epoxy resin, when the hot coat is set, and say if I want to sand out any imperfections before the gloss coat, what grit would you recommend starting at and going up to? And would you just use a random orbital sander for this?

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Sanding your hotcoat with Epoxy we start at 80 grit, we use a Variable Speed Polisher / Sander with a FlexPad Sanding Pad but an orbital sander will work; it will just take longer.

4. What's the best way to sand a double concave hotcoat? I have a medium and soft 8 inch Flexpad but I'm not getting the deep part of the concave. Can I use the soft pad with 150 grit to get rid of the shinies?

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Yes, you can use the soft pad with 150 grit. If you keep it flat with a light touch it will bend into the concave and sand the bottom of the concave.

Don't worry about getting all the shinies. Just get as many as you can without over sanding (sanding through) and you can always touch up the leftover shinies by hand.

5. I sanded through the hotcoat in some spots and can see the fiberglass weave. My question is do I simply coat the spots with weave exposed and then re sand? If so what grit should I start sanding with ?

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It's best to lay a "gloss coat" over the entire board to fill the weave. You'll use less resin that on the hotcoat. I don't know what size your board is so here's a resin usage chart (check out the gloss coat column)


Lay it down and walk away. You can sand it with 320 or 400 grit when cured and good to go!


6. How do I sand the gloss coat to eliminate scratches and make it shiny?

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The shine of your gloss coat will depend on the levels of sanding you choose to do. Each progressive grit will sand out the scratches of the previous grit. A super shiny gloss will progress from 320, 400, 600, 800, 1000, to 1200 grit or more if you wish. Then compound with a wool bonnet and polish with a foam polishing pad.


You can choose to sand up to any grit, compound and polish. It all looks good. Just depends on how much "depth" of shiny-ness you're looking for.


7. Took some 80 grit to my hot coat and I can see where I burned through. If I'm going to do another hot coat, do I continue to sand so all the marks come off from the 80 grit or do I just do my next hot coat?

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Basically you'll be laying down a gloss coat... Continue sanding your board to 150 and get all the bumps and dips out of it. This will make your gloss coat flat and very easy to sand. 


When the gloss coat is cured give it a day before sanding, the resin will be harder and the sandpaper will cut it better. 


Start sanding at 320 or 400 depending on how flat the gloss turns out. It'll be hard to burn through again at those grits and you'll have a good looking board. You can continue to wetsand through higher grits , compound and polish to give your board a real nice shine if you'd like.


8. How to I grind the lip of a 10.5 centerfin box down?

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The centerfin box is installed after the hotcoat, before sanding the board. The lip of the box will be sanded down flush with the bottom of the board during the sanding process. We recommend "grinding" the fin box plastic with 60 or 80 grit and a hard or medium flexpad. 


Grinding is a bit different than sanding whereas you tilt the sanding pad up a little bit to use just the edge of pad to focus the force right where you need it (on the box plastic). Sanding is done by keeping the pad flat on the board and removing a broader area of hotcoat. 


Grind the finbox plastic down for a few seconds and let it cool for a few seconds as too much friction will actually melt the plastic and the heat can possibly transfer into the foam and weaken the area around the box. So it's best to cycle the grinding a few seconds on, a few seconds off.


Grind the box down as close as you're comfortable with without hitting the hotcoat. Then proceeed to sand the entire board with the flexpad flat and as you pass over the finbox it will sand evenly with the hotcoat.

9. What is the difference between sanding and 'grinding'?

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 We recommend "grinding" the fin box plastic with 60 or 80 grit and a hard or medium flexpad. 


Grinding is a bit different than sanding whereas you tilt the sanding pad up a little bit to use just the edge of pad to focus the force right where you need it (on the box plastic). Sanding is done by keeping the pad flat on the board and removing a broader area of hotcoat. 

entire board with the flexpad flat and as you pass over the finbox it will sand evenly with the hotcoat.

10. My FCS X-2 plugs are melting when sanding them down

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The heat from sanding friction will cause epoxy to soften then re-harden. It's best to sand a plug for 10 seconds or so then move to another plug, making your way around them. By the time you get to the first plug it will be cold again and sand nicely.

11. Velcro face sanding pads or cloth face Flexpads better for sanding?

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We have cloth face Flexpads in stock. Velcro faced pads are special order. We do not stock velcro because the hook and loop is not a flat surface when sanding and creates swirl marks due to the velcro flexing with pressure. 

Cloth face sanding pads with PSA sanding discs provide a better sanding finish in our experience.

12. I have a lot of really tiny air bubbles that are filling up with dust during sanding and making my tint job look bad

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It sounds like you have pin holes in the hotcoat which is caused by dust settling into the hotcoat as it cures. When you sand the board the sanding dust gets caught up in these little pin holes. In the end you won't see the imperfections that much but it is best to blow out the dust with compressed air and follow up with a needle to scrape out what's left. Not worth the needle effort as far as I'm concerned, like I said you won't see most of them when glossed over.

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