Prep the ding

Hi guys! I have browsed and searched this forum for a specific problem I encounter with ding-repairs. I wan’t to make my repairs more flush. Can anyone give me pointers to what I should look for when I sand around the ding? Should I sand just barely through the hot coat, or should I stop as soon as the “hair-like” shiny fibers are visible?  Maby there is a high-def photo of an example of when to stop sanding? Regards from Eirik

Hi Eirik,

As my old philosophy/ethics instructor used to say, That depends….  every repair is different. I can’t be more specific without the specific repair. 

A little shatter, just get into the hotcoat, brushing on resin well to fill the cracks, sand, polish.  Something more major, where you need to fill over crushed and damaged foam and ideally behind the original laminate, you’re going to want to laminate cloth over it, followed by a filler coat of resin and a gloss with sanding and polishing involved for the best appearance. 

As a general rule, don’t sand into the glass if you don’t have to. If you do, make your repair big enough so that you can sand the edges of your repair very gradually down to nothing (feathering it out) and still leave the damaged area covered with good new glass cloth at full thickness for strength and durability. Make your filler coat bigger still, feather that, gloss coat bigger still, wet sand and polish that. 

It won’t be perfectly flush, but it can be invisible to the eye or to the touch, That’s what you are looking for.The amount it’s out won’t be visible, indeed most boards are not symmetrical to that degree anyhow.  

hope that’s of use

doc…

Thank you very much for the thorough explanation doc! This was very helpful.

Im fixing a board for a friend, it’s epoxy. It has multiple dings, one on the rail near the nose. Two dings on the deck far up, and also one ding just where the end of the sidefin rest (the finbox does not seem affected by the ding). I have sanded and removed damaged glass, and filled with q-cells. And I have laminated all the dings. If I study the lamination from the side, it does not look like it builds much at all. But the sharp edges seems large if I let my hand slide over them. So I don’t think I have so much material to work with when it comes to the feathering you mention above. But it will be watertight and functional. And now I understand why I should put bigger patches, and even bigger coatings.

 So if I have to replace some damaged foam, you recommend that I try to squeese the q-cell in, to compromise as little glass as possible? Only remove shards? 

Regards Eirik

Hi Eirik,

Let me go at this in reverse order-

I like to cut the crushed foam away from the underside of the lamination, the X-acto knife or similar scalpel-like tool is really good for that, Pull the  lamination up to flush or close to it. Save the shards too, as much as you reasonably can, embed them ( as well as you can ) on the surface of your filler. Like a jigsaw puzzle. Try to limit the amount of filler that shows.  Then. laminate over all of it for strength and smoothness. And again, laminate big. 

It always makes me shudder when I see somebody contemplating using a saw or a router for a repair. I used the scalpel as a surgical analogy above, staying with that analogy you are trying to be as minimally invasive as you can be, for the best job. It’s less work over the whole of the job and you get the best results, close to invisible. 

Now, for the ones you’ve done already- nobody says you can’t sand them a little more, smooth them out more. If you still have sufficient overlap onto the original glass after that, great, you will probably want to brush on a finish coat of resin after, but that’s okay. If you don’t have enough, well, sand it all very smooth and as flush as you can and now you can put on that bigger cloth patch. Which will be around 1 mm thick or less at the thickest, won’t really matter, no?

hope that’s of use

doc…

Thanks doc! For my next repairs I will use your method:-) I always use a stanley-knife for the prepping, but the blade gets poor really fast. I always thought I should get a router to work more tidy and get a controlled basis/prep, but I see now what you mean about being less invasive to the original structure. I will try to sand these repairs and then coat with resin. I will try to put on a bigger patch on the ding near the fin, but then I have to laminate over the finbox. I’ll tape the hole in the box and cut away this cloth covering the tape when it has hardened enough. 

Most guys use Q-cell to fill dings.  I like to mix it thick so that it doesn’t drain out of the ding.  You can squeege it into the ding with a plastic spreader.  You want to squeege it onto the ding in such a way that leaves a bit of a bump.  If you try to squeege it flat the Q-cell mix will shrink below the surface and you will have to reapply more Q-cell.  If you get the right amount in the ding, it will sand flat easily.  Then apply a layer of cloth, hot coat, sand, gloss and polish to finish.  If you don’t sand properly around the ding; cloth and coats of resin will not stick.

Right? Better not to have to deal with a great gaping hole. There are times and places for routers and saws, but very few of them. 

Be very careful around the fin box. Double or triple tape, maybe stuff some wax in there, getting resin out of one of those is nothing like fun. 

A couple of other things- don’t use a sanding block on anything but very flat surfaces. Ugly things happen, you sand the corners off rails and so forth. 

And listen to McDing. He’s good, he is. 

hope that’s of use

doc…

Thank you doc and mcding for sharing from your valuable insights:-)

Repair your ding in a manner that you don’t have to do much sanding in the finish coat.   Lots of little tricks from tools to techniques.  Things like using a surform or flat file to take down your repair while the resin is still soft.  Strategic use of plastic or wax paper to cover the repair as it cures.  How you thin and brush on your final coat of resin.  All things that make it easier to blend in a ding.

Thank you mako224! I’m sure these tricks will come in handy for my future projects:-)

…hello;

I want to say that in the instant that you decided to start to sanding the glass work you ALWAYS should use fiberglass, not only resin as said here.

Then; if you need to fill you always use the core material to do that then an smear of silice with resin etc (also under the core material to glue it) then sanding then lamination etc.

You always sand to the first lamination layer then use styrene monomere to check if you need to sand more.

The only problem is presented when the board has a tint; or pinlines; gloss polished etc. You need to take count of all that stages and layers to have all leveled. In most cases with tints is not possible to obtain the color; will be darker if you do not have to fill or brighter if you need to fill. If the best situatuation is to spray the area to try to mimic the color work, you need to sand a big area around previously.

All the dings should be sanded at least 2 times bigger than the ding itself to have a good base and to feather everything.

Resin is a glue; the combination with fibers makes the glass work strong. Do not rely on resin only.

All that is from a surfboard builder perspective not a ding repair perspective but you can ruin a fine board doing a crappy repair.

Thank you very much for the feedback reverb! Just to clarify; I laminated all of the dings in this project. But I must say that it’s tempting to ligthly sand an brush a little resin along the rail on my 5 year old PU board if it starts to get spiderwebs etc. all along the rails (im not sure what the translation is for these cracks in the glass that can occur over time).

I didn’t quite catch this test: “You always sand to the first lamination layer then use styrene monomere to check if you need to sand more.” Do you mean the initial sanding before filling and laminating the ding? And do you mean to the outermost layer? Will the styrene monomere hide the fibers if I haven’t sanded enough?

The dings I have been working on so far in my repair-career haven’t been so deep, so I thought q-cell would suffice. The alternative is to route and fill with original foam? In this case I would have to order some foam from overseas, or use packaging foam?

My goal at this stage is to make the dings waterproof and structural correct, and to improve my skills in the delicate craft of sanding. My sanding feels a bit all over the place.

Regards from Eirik

 

 

Hi; yes; I mean the initial sanding. The styrene is to check if everything is correct. It shows what surface should need to go and what can stay there. Dry and with the dust you cannot see clearly all those details.

The spyder webs are not on the surface but under so you do not need to do anything. Some, at a point can crack or hairlines the surface and in that case you sand as I mentioned: to the first layer (the layer to the core-the foam-) then styrene; then check then sand double the area of the ding then you are ready to proceed with the lamination or the filler in any case.

If you do not sand deeper as you say, you cannot obtain an smooth surface due to you need to add all the layers that the glass work have and try to mimic the finish surface.

Remember, if you use a filler you need to put at least 1 sheet of fiber on top then the hot coat; then sand, then the finish coat.

The process is always the same no matter if is a board or a ding repair or a pool or a boat etc You get rid of the problematic and damaged fibers etc then laminate (or fill then laminate) then the hot coat (a filler coat) then a finish coat (polished or buffed) or sprayed.

Thank you again reverb:-) I’ll see if I can order some styrene monomer the next time I run out of resins and materials. 

Here is a photo of the dings near the nose. Please don’t laugh about the nosejob I did for my friend at least 8 years ago, with brown microballons, white pigments, non-surfboard-cloth and horrible sanding/coating. My next step now is to find a good place to do the sanding (it’s less than 10 degrees celcuis outside, and heavy rain). Then clean everything with acetone. I’m considering coating all the area above the tape since there is some exposed fibers from my previous mistakes.

Just remember that sloppy work makes for more work and more sanding.  I think back to when my father taught me to tape drywall.  The goal of a good taper is to do such a good job that hardly any sanding is needed.  I try to keep that in mind when doing ding repairs.  Here is another good tip.  Get a couple of yards of 2 oz cloth for ding repairs.  Works fantastic and blends easily. 

Also if you can source some plastic similar to what you find in a sun cure ding repair kit that stuff is golden for dings on the flats.  On a puncture type ding using a piece of this plastic I can complete a repair with almost no final sanding.  Print shops that do laminating throw this plastic out regularly.

Thank you again mako224. I will be on the lookout for some lighter cloth. I have som packaging plastic from work I can use, I have already tried it with som fiberfilled solarez on a minor ding on another board. But it didn’t strike my mind that I could use sheets on top of laminating.

Funny you mentioned dry-wall taping, great analogy! We just hired a professional painter to help out with som drywalls at home, and I asked him if I should cover the door-opening etc. with some plastic, but he said exactly the same as you; “it’s gonna be very little sanding needed”. And if I remeber correctly they also lay the 3 layers of compound on top of the tape bigger and bigger to blend better.

Eight years?  Must be a “magic” board.  I would have shaped  a new one by now.

The drywall analogy is a good one and is sooo true.  Why make work for yourself?  4 oz is the best for ding repair because it disappears and can be multilayered if needed.  4oz is all you need to keep around .  Don’t use the Bondo shit resin from “Home Depot”. Get yourself a quart or pint of real surfboard resin(Silmar 249) from one of the mail order suppliers like FoamEZ or Greenlight.   Also a container of Q-cell for filler.  Putting a filler in a ding or brushing Solrez over a ding is not an effective watertight repair.

Yeah this board has definitely seen better days. But at least it’s a cheap way for my friend to get into surfing again, and good ding-repair practice for me. He has stored it for a long time. :slight_smile: