hotcoat issues

As of latly I have been getting a lot of fisheyes/ dry spots in my hotcoat. Heres the process on how i get to hotcoating.

I do not seal my blanks, and I am using Research Resin 2100 fast hardener, no Additive F

 first I laminate the bottom of the board using cut lap lines, I flip about an hour and a half, after i finish the lay up, and cut the lap lines. Let sit for another 2 hours.

Second Laminate the top using cut lap lines, and same play out as first step, except once the resin is fully set, I tape off rails and hotcoat top. At no point thru this process do i lay a bare finger on the board. I am using wax paper to flip and the board also sits on wax paper while im cutting lap lines. I wear latex gloves while taping off the rail for hotcoating.

Orginaly I thought the additive F was causing the fisheyes/dry spots, because i noticed a lot of debry in the chemical. I stopped using additive F and am sitll getting the dry spots.

My final though before sending out this was, that the resin was seeping thru the lam where there was any little space below it. So after I lam'd this last board i ran a strip of resin down the stringer, and along the lap line to fill any gap there could be.  I still ended up getting the same type of dry spots, but not as severe along the stringer.

The reason i say dry spots over fish eyes is because there are small areas on the board that are almost completly resin free, like i dint hit them while hotcoating and i know i did for sure.

Has anyone ever had this kind of problem? Is it because i dont seal my boards? Does a spackle seal really make a board that much weaker?

It could be the resin from your lam soaking through the glass and filling the little voids in the eps foam leaving dry spots and pinholes in your lam.I’ve had this in large patches everywhere on the board to one little dot.A friend of mine recently glassed an eps board,when he did the hotcoat he mixed a smaller batch of resin and applied it to the board with his  glassing spreader and pressed the resin into the weave to fill any pinoles and dry spots.He then mixed his actual hotcoat right away,poured it on and brushed it out and says it leveled out nice with no fish eyes or dry spots.He did this on both sides of a 10’x34"x4.5" sup and said it worked great.Do you have a pic?It sounds like you just have large patches of pinholes creating the appearance of a dry spot in the hotcoat.

Maybe use aluminum foil instead of wax paper?  Fisheyes are generally from contamination.  Wax paper could be the culprit.

you are the perfect guy to answer my question. I build my blanks the same as you( ive seen some of your posts). I am thinking its exactly what your saying. I was planning on spreading a thin layer before hotcoating the bottom But i wasnt sure how long to wait to do the acctual hotcoat. So ill pressit in good with the spreader then mix up my resin and brush it on, then report back. it wil probally be an hour or 2 thou. thanks for the info.
What kind of fin system are you using?

I’m using probox fin system,and then the finsunlimited longboard boxes.John has a good point about the wax paper possibly contaminating the surface before you hotcoat.I keep a roll of cabinet liner in my glassing area and have my glassing stands wrapped with it.I also cut a clean piece and lay it over the stands,they keep the board from sliding around when glassing.If the piece gets funky I throw it to the side and put a new one on,a 3$ roll last me almost a year.

My take is that it is just the nature of epoxy.  Next time you are mixing some up, look closely at the surface.  The hardener and epoxy seem to have two different surface tensions.  Even when completely mixed, it won’t flow smoothly. 

Painters use Penetrol to get oil based paints to flow better and have a more uniform sheen.  I think the answer lies in surface tension modification, rather than thinning with zylene and adding wax.

But I’m not a chemist, and could be totally wrong.

I was also debating on the wax paper being the problem. However, there is really never any dryness where the wax paper sits on the stand or along the rails. I also though it maybe just spreading the contamination, but you would still think where the wax paper is touching while im cutting lap lines would be the most contaminated area. 

Does the cabnit liner or aluminum foil stick to the board? The board is sometimes a little tacky yet when i flip to cut the lap lines, this is why i have been using wax paper, Dint really think of an alternative material that wouldnt leave any marks on the board besides wax paper or freezer paper.  Oh if you use wax paper for anything, ya might try freezer paper, it works much better at not adhearing to resin's.

very intersting thoughts there everysurfer, At one point I would mix my Hotcoat resin very gently, as to have as few of bubbles as possible, So i would jsut sit there and slowly stir for like 3-5 mins until the resin changed color and the epoxy and hardner became one..   .. .. .. .. well that wasnt the issuse. I was thinking the little bubbles might be where the fisheyes were coming from :o)

Well hotcoated the bottom. DId the resin spread, then applied hotcoat. Looks pretty good, There is some dust particles here and there but i can deal with that. Had a 2 or 3 sink holes along the stringer so i just dropped a little resin on them and walked away.  Pretty stoked thanks for the insight jesus


You ever think about making your own fin boxes and fins? I did the research on making molds and that part seems very doable, I havnt really looked into 2 part plastic's though.

"no Additive F" ???  In your first comment?

Many of the issues I thought I had with contamination were solved by using the appropriate amount of Additive F.

Bubbles, pinholes, dry spots etc... Now I use it liberally and have had no problems. Also dust, air compressor in the room, and the blank gassing can also be annoying problems with epoxy. The foil definitely does work better than wax paper. Your last comment about sink holes along the stringer is telling. Could have been just some small voids in the glue up...or...again the blank is "gassing" (maybe the wrong term) but temperature changes making the blank suck air or expanding and "gassing". I always try to wait to use epoxy as the day is cooling off and the blank is shrinking rather than expanding. "sinkholes" as you noted are way easier to deal with and you can just rub it a little with you finger tip and it will fill in.  My two cents worth anyway!

Glad things turned out well!