What is Surfacing Agent

As a chemist, what is Surfacing Agent?

what are the chemical components if anyone knows?


Usually paraffin melted into xylene or styrene

I guess you could look those chemicals up

like here:



neither benzene derivatives aren’t terribly good for your health

great for gel coats

So could you potentially wipe a thin layer of melted paraffin on a board’s lam coat or tacky hot coat to make it hard?

definitely xylene and styrene aren’t chemicals that you would want long term exposure to so a chemical respirator is a must.




I think you would qualify as a Surfing Agent? A Secret Surfing Agent Man (SSAM)

Howzit USOM2000, sounds like you're a little confused about SA. You have 3 choices, you can just but sanding resin which already has SA in it or you can buy SA at or from a surfboard materials shop or you can make your own. To make it you need the styrene and some parafin wax, just shave the wax into the styrene and it will desolve and there's your SA. I think it's about 6% wax for a good SA ( i just eyeball it).Aloha,Kokua

Talcum powder is great for helping get rid of lam tack if you have already made the mistake of using lam instead of filler resin. Gelcoats have no wax in them flowcoats have wax in them.


that is a good tip with the talc

so here is the story. I added 2% SA to my bottom hotcoat which stayed tacky for days. I tried to sand it but got so fed up that i rehotcoated and covered it after it had hardened with wax paper. That came out great, really hard and easy to sand. With the top hotcoat, i used 5% SA and still had the same tack problem. I used the wax paper trick and got about 90% coverage, now nice and hard, but there are still spots that are gummy. Just looking for a way to cure my sanding blues. I just bought sanding resin and will use that from now on, forget messing with SA.

thanks all for the response


10% styrene and 5% wax is what I use for my polyester hot coats. Works very nicely I find. You want to add enough catatlyst for the resin to gel in about 5-10 minutes after walking away from it as well in my opinion.

…for 10 L of styrene 200 gr of paraffin

thats the formula


the tacky problem may be is due to the weather or bad mekp or diluted resin (yes some retailers do that)

sometimes is the brand of the resin

but normally this problem is not in the hotcoat but in the gloss coat

Speaking as a former…long time ago…chemistry tutor and TA…

Surfacing agent is a styrene-soluble wax, such that it tends to float to the surface of the polyester resin ( hence a lower specific gravity than the resin ) and act as a barrier betwixt the air and the resin, such that the polyester resin hardens completely. Kinda like a soap film or the alkane of your choice on water.

This is the MSDS on the stuff, more info here .

Basicly, hit the old CRC manuals, if you find a wax you can get easily that’s fairly soluble in styrene, it’ll work for ya. I found that the older editions of the CRC are better when it comes to solubilities.

Hope that’s of use


  Howzit USOM2000, By any chance are you using UV resin? If so that be the reason your hot coats are tacky. The wax paper trick is an old one used for ding repair since the heat from the kicking resin sucks the wax out of the paper. When using UV rsin you need to add more SA and let the board sit for about 10 minutes before putting in the sun or under UV lighting.Aloha,Kokua