hot coat question: filling in the weave

General Discussion
1

i recently tried hot coating the bottom of my board, and it appears that i did not let enough epoxy sit on the board so that it would fill in the weave completely. there are some “dry” spots where i can feel the weave’s coarse texture instead of the smooth hot coat. my question is, when you hot coat, are you supposed to let as little resin drip off the board as possible? are you supposed to keep a full thin layer of the resin over the weave and not let any drip off the rails? i figured that spreading it over the weave while still having some run off would be enough to fill in the gaps of the weave, but apparently i was wrong. should i go over it again and keep a good layer of resin on top of the board this time?

thanks

2

It actually sounds like you went a little too thick. If you put it on too thick & let it kick too slow (or with epoxy) as the resin molecules start to bind together, you can get void areas where it separates as it runs downhill.

If it was poly, kick it faster (more catalyst). If it was epoxy, heat up the resin first (before mixing in the hardener) so it runs like water, and then put it on with a small, firm foam roller from the paint department.

You can go back & fill those voids with small amounts of new resin. Do it before you sand. You’ll get little round raised areas that require a little more sanding than a smooth hotcoat/fillcoat, but you haven’t screwed anything up that isn’t easily fixable.

Check out the paper under this board - this is after using epoxy fill coats on both sides - less than 20 drips, total. The biggest blob is right under the nose from hotcoating the bottom. Heat it up & lay it down smooth & you can walk away.

3

Thanks Cross and Benny, Thats exactly where I’m at on an epoxy weave fill process.

4

thanks for the help Benny,

im using epoxy, but im not too clear on what you mean by heating it up. how do you go about doing this? and the purpose of this is to make it cure faster?

thanks for the help.

5

You can use a so-called"cheater coat" with epoxy or poly. I have heard that you can heat epoxy in a micro-wave oven but haven’t tried that one myself yet. The cheater coat is applied after your lamination has started to go off. Catalyze some lam resin and squeege it on with a yellow plastic squeege. This will fill the weave.

6

I stand the resin container in a bucket of warm water before adding the catalyst (also warmed). Some experiments are needed to make sure it’s not so hot that it’ll cure before you finish applying it. If you find the weave is not completely filled when you have hot coated, let it kick (thicken) and apply more resin over the bad area. Let the whole thing cure and get on with the wet & dry / polishing. It works for me.

I bought one of those slick thermometers that work on magic, you point it at the resin and it tells you the temp, no getting the thing sticky. For a while now I have monitored resin temp, blank temp and geltime. I’m somewhere knowing exactly how long I’ve got to work the resin in or complete painting on the fillcoat. I muck around a lot with resin infusion and this data becomes REALLY handy then!

7

Yep, putting your resin jug or can in a bucket of hot water is foolproof. If you get home from work early enough, just take the resin jug (& hardener) outside and put them in direct sun for a couple hours. In the winter, I pour the resin (only) into a metal can & set it on an electric hot plate, but I’ve also had scary times with that, so I wouldn’t recommend you do that at first.

However you heat it, just give the can or bottle a little shake after a while. If it still moves like honey, its not ready. If you hear a slosh like water inside, go ahead & measure & mix.

Don’t look down the hole, though, as if its runny it can slosh right up into your eye.

You’ll know as soon as you start to pour if your resin is flowing like water. If it goops, pour it back & start over. If it runs, go ahead & hotcoat. It’s not a pro-level secret; it only takes a couple times to see what I mean.

Wear your respirator & protective clothes & gloves! The thinner the resin gets, the easier it can get inside you.

8

If you have access to it, heat up the resin (not the hardener and NOT both together) in a microwave for 10-18 seconds depending on the amount and it flows much better.

There is another possibility of what happended, I think. Are you using EPS??

I did a board recently (2# EPS) and I taped off the top to do cutlaps, and I think when I pulled off the masking from the top, the area of tape near the tail pulled up the seal/spackle. When I lammed it had what looked like a dryer spot, and then when I hotcoated it, even though I did completely cover the whole top of the board with resin, while it set it must have drained away in that spot because I was left with weave showing again on that spot.

Just a thought…

9

if the epoxy is a more watery consistency, wont it tend to run off the board more easily? or will it cure faster if it is more watery in which case i wouldnt need to worry about the hot coat sliding off the board while it cures?

i feel like i did the hot coat in a manner that was more like laminating, ie. running the resin off the edge of the board. next time i will just spread it evenly so there is a thick enough coat to cover the weave, while not running off the edge of the board. i pulled too much off the ends of the board while i was painting it on. ended up with too little actually on the surface of the board.

thanks for the help

10

It will run off the board more easily, but it will also cure faster, so one balances the other out. Also, when the resin hits the board which is much cooler, it will thicken up, and right away. Both of these things keep the resin on the weave.

Also, temperature and any thinners/additives you use will change how the resin behaves. I have found a formula that works very well for me to fill in 6 oz. weave with RR Epoxy.

Room Temp: 75 deg

Resin: 1-1.5 oz. per foot of board, microwaved 2 sec per oz of resin in 1300 watt microwave

Add F: 1cc per oz of resin (this comes out to 2cc per ounce of hardener, as recommended)

Denatured Alcohol: 0.5cc per ounce of resin

This makes for a hotcoat that stays thick enough to cover the weave and laplines. For gloss, I just use 1cc denatured alcohol per ounce of resin. Makes for a thinner coat with better level-out.

When you initially get the resin on, move quickly so that the hot, thin resin will fill in all the nooks and crannies in the weave. Once the resin cools from touching the board, moving the resin with a brush to fresh weave can result in little air bubbles in the pockets in between the fibers, like a checkerboard pattern. One set of cross-strokes, walkout, and walk away. It is time sensitive, and I have had hotcoats that showed brush strokes on the side I walked out last.

I still have yet to try heating the board up to keep the resin thinner, but I am afraid of outgassing. Does anyone do this successfully?

I have no idea how folks like Benny can use so little resin…Maybe I’ll have to give that roller a try. Benny, can you tell us how you go about hotcoating with a roller?

JSS

11

Hey Cross,

Here’s a method worth trying with epoxy if you’re doing freelaps. After the bottom is laminated you’ll knock of the high spot where the lap ends before you laminate the deck. When all the lamination work is cured sand where the laps end on both sides and get them faired resonably. Paint a little baste coat on the irregularities and once it’s cured reshape the areas of the board so it’s real close but don’t be too aggressive. Now mix a little resin with some q-cell and squeege the whole board with the stuff you’ll find all the highs and lows this way and you’ll be able the return the board to it’s original shape with some hand block sanding. Now you ready for your fill coat. Tape the rails and do the deck first. I prefer a nice wide throw away brush. Once you get the material on the board brush it athwart ships, stem to stern, athwart ships, and finally stem to stern. Now take a heat gun on a moderate setting an work you way from one end to the other. You will see all the trapped air evacuate and the resin will level beautifully.

No need to be wastefull but going a little generous with resin is a good idea IMHO it makes for a much easier finishing process.

The most important work and the most time consuming part of any project is in the preperation.

Have fun, Rich

12

Rich,

Does the q-cell/epoxy mix up and cure clear? I was wondering if it would make the grain in a stringer or any graphics milkier…

JSS

13

I use a firm foam roller to hotcoat, not a brush. Its about 4" long and 1.25" diameter and white. It picks up a lot less resin than a brush, so I’m throwing away less when I’m done.

The other trick is to pour a bead only about 3/16" thick down the length of the board with one hand while the other hand follows with the roller. I start in the middle, pour a stripe down the center, next stripe is 6" away - the center stripe spread to the width of the roller - and one above the rail finishes it. Walk to the other side & 2 stripes to go. Then do the criss-cross pattern like with a brush to push a little resin towards the rails. One sweep around the perimeter of the board to wet the rails and you’re done. Sometimes 2, if the rails are thick, as the roller can’t get all the surfaces with just one angle. Then, I admit I wait about 10 minutes (one beer) and roll once right at the tape line to pick up the biggest drips.

That’s all - it should be setting up by now.

It helps a ton (but is not necessary) if your lamination only went on 3-12 hours earlier. When the lam is still tacky, the fill coat will really hold on. I haven’t had a void - or wasted resin - in many, many boards.

Laminating takes 1 oz per foot of board for one layer of 4 oz; 1.5 oz for one layer of 6 oz, about 1.75 for 2 layers of 4 oz. Fillcoating takes 1 oz per foot and you will probably have a 1/16" deep pool left in your bucket. This little bit can be really useful: I come back in about an hour and if there are any pins or bubbles or zits, I scoop a bit of resin from the bucket (should be the consistency of peanut butter) out with the point of a small nail & drip it into the spot. It may level out, or it may leave a slight bump to be sanded off, but either way is better than a void or a hole.

14

Thanks Ben!

JSS

15

thanks guys, but seems like mixed messages are being sent though, im still unclear if you have to heat both the epoxy and hardener up? (seperately of course) or just the epoxy meaning the hardener stays the same honey like consistency while the epoxy is watery?

16

Sorry I didn’t mention that. Since the hardener is ‘thinner’ than the resin, I just put it in the same bath of hot water (an old Tupperware container) as the Add F (if Add F is too cold, some precipitate forms). I just use the hot water from the house, around 130 deg F. I submerge the containers of Add F and hardener first, so the Add F and hardener will be warm when I am mixing stuff up around 15 minutes from then, after taping off and getting things ready. The resin is thicker, so it needs to be hotter to get the same viscosity, hence the microwave. I do not warm the denatured alcohol, it evaporates fast enough as it is at room temp.

Also, I keep my hardener in the quart sized bottle (the gallon won’t fit in the tupperware container), and just refill it often.

Hope that answers your question…

JSS

17

so you are saying yes, it is necessary to heat up both the epoxy and the hardener. i will try doing this once im all good to start working again.

thanks for the help

18

Be careful about the volume and the container width. And the environmental temperature.

The first time I did this it was in a narrow container in my shed on a 39ºC (102ºF) day.

Those with experience in such things are now wincing in anticipation of the resulting exothermic reaction.

They wouldn’t have been disappointed.

19

It just depends on how cold they were.

With Fiberglass Hawaii, which is a 1:1, they both go out in the sun. RR, at 2:1, I’d probably just put out the resin, it kicks faster than the others anyway. With the Tap stuff I sometimes use (4:1), only the resin. Or both. Or neither. Like, if the shop is 50*, I don’t use epoxy. If its 60*, I heat just the resin on the hotplate. 65* inside but sunny, they both go out in the sun. 70* inside & out, resin into a pot of water. See? No easy answers.

Sorry, but its like that.

20

Yo Max,

You don’t mix much q-cell in at all. Just enought to lend a slight bit of thickness to the material. You won’t put it on very thick either. You might use 3 or 4 oz of material on either side of a 9’0". It’s just enought to get the board to the stage where you can make it perfectly fair for the final fill coat. If all the irregularities are gone when you fill coat the board you get a beautifully smooth surface that you can work with very fine grit to start with. This way you have layed the insurance you need to know you’ll have no sand throughs. Laminating always leaves a few highs and lows that need to disappear before you get serious about you final processes.

No Worries, Rich