Additive F & Epoxy

Good evening all,

I am fairly new to shaping, and have a question about additive F. Do you have to use Resin Research with it, or will any epoxy do? I thought I read somewhere that it has to be RR. Anyone who has used it with other resins please help me out.



Other brands should have there own equivalent. For example, I beleive that Fiberglass Hawaii Aluzine calls theres’ Surfacing Agent (or Sanding agent- something like that).

Whatever brand your using, check out their website.

Good stuff, just don’t over do-it or you might end up with bonding issues, particularly in small batches.

I haven’t used it in a long time and I don’t miss it at all.

IIRC, the folks that need it are in cold and/or humid places.

Every epoxy system has different chemistry and charateristics. It’s best to stick with the manufacturer’s suggestions.

For example, Resin Research used Additive F to lay down a nice, sandable hotcoat while Entropy SuperSAP does not require any additives for a hotcoat.

Humidity/moisture and carbon dioxide – amine blush.

additive F is xylene and parafin. It will work with any epoxy resin and used in paint application also($17 a gallon at sherwin and williams). As mentioned above, many higher quality resins do not require keeping this fire hazard in your shop to get a perfect finish. With all the resin options available, keeping things simple usually means less chance of mistakes. If acheiving better flow in low temp climates is an issue just warm your epoxy. If you already bought your RR you need xylene and parafin surfacing agent for applications after initial lamination, whatever brand or home made surfacing for epoxy will do the job.

Strange question…Really…

add F is a Resin Research product. If you’re not using RR why do you worry about add F ???

My workshop is warm and dry. I use Add F for all my lams and hot coats. Awesome stuff !  Follow the rules.

I use it with other brand with no problems.
You can do without with RR if you work in dry warm place, same for all époxy. By avoid blush because of humidity addf improve curing of surface for better sanding and adhésion, plus it thinned époxy that improve flowing. Warm do the same.

I used RR epoxy for many years before additive F was available. I used additive F in my green room epoxy for about 18months. For mostly habit with past great results and flow concerns. When I found out that it wasn’t necessary for green room use I noticed no difference and one less chance of making a mistake.

Pic initial lam with green room. no pic of filler coat but applied wiht 3" chip brush about 10-15 minutes after lamination just past sticky. Temp in glassing area about 95degrees F and used westcoast fast hardener for both lamination and filler coat.


FINAL EPOXY COAT(aka gloss coat) prep

I have a laminated top and bottom board with a filler coat on both sides. Totally sanded back to shape and all the pre install fin boxes and leash plug is exposed. This board is water tight, I could surf it now if I wanted to. I wash all the sanding dust with water then soap and water scrubby thingy it ,then rinse and dry it off. My hands are clean so I am not afraid to touch it. I had to blow off a few specs of sanding dust in scratches that didn’t come off with the wash.   

Pic of scrubbing board and rising off. Note to self. Don’t change the truck transmission oil prior to taking board to glassing rack. My hands are very clean. I will use my hand sensitiviey to feel for micro boogers prior to taping off board for FINAL COAT.

Made in China Chip brush Prep.

The 4"  double thick chip brush went up in price at home despot and lowes about 18 mos ago. The cost 4.79 at those places. I get min on amzon with free shipping for about $1.70 per brush. Getting excess bristles out is your goal for the prep of these burshes

  1. pound on something hard

  2. Pull at bristles with clean hand

  3. Tape off to further help keep bristles off FINAL COAT


Deck FINAL COAT with green room resin blanco and west coast fast hardener. Did this a 5 pm Sat afternoon. Glassing area temperature at 105 degrees F. Was able to pull tape in 15 minutes. I would not do this with a straight up foam board. This board was sealed tight so I proceeded. NO SURFACING AGENT USED


Did the bottom at 630 Sunday morning. Flipped board, razor blade scraped tape off line on rail from deck FINAL COAT. Wiped with clean rag and checked for micro boogers with clean hand. Tape off fin boxes and rail. Chip brush prep. Glassing air temp was 78 degrees F. Green Room blanco resin with west coast fast hardener and of course no surfacing agent. Pulled tape at 30 minutes and it probably could have been pulled 10 minutes earlier.  This board will next be sanded Monday(because I don’t want to work on it today) starting at 200 grit and you can take to polish or spay finish of choice.

First brush your chip brushes on some wide tape until all the stray hairs are gone.

all the best.


Wow…thanks for the photos and writeup! What would you do different if the board was foam? Thanks, J

Good info all. So i forgot to mention. I am actually deployed in afghanistan and building the board in a connex. Our humidity here is around 0%. Thats not an exaggeration. Should i even bother with the additive F? Is the sanding benefit that great?

Deployment suck!

when laminating eps foam boards by hand(not vac bagging) you have to consider the eps blank could be gassing out expanding air molecules in hot environments and could cause problems. I never do non vac bagged boards to initially seal them. Unfortunately giving info verbally is tricky because in reality I am considering dozens of variables with every process of the board build that could never be accurately described briefly. 

I am still not sure what brand resin you are using???