A. Application Technique
B. Compatablity
C. Durability
D. Cosmetics
A. same…brush it on
B. epoxy will bond chemically to polyester, but polyester will NOT make a chemical bond to epoxy. you’d need to rough up your epoxy so that the poly can form an adequate mechanical bond.
C. unreinforced epoxy resin is far stronger than unreinforced poly resin. in fact, i finish with RR 2020 epoxy for greater impact resistance and more shine.
D. word on the street is poly gives a better shine, but i’m more than pleased with what i get from 2 coats of RR 2020 w/ additive F over my lam.
2 cents worth. I made my first board start to finish with epoxy and wile polishing dropped it to the concete only to find very minor scratches. Second board I thought I would finish with poly. Sure was easier but it gets impact and chips,where if it was all poly it would have been a ding. Never again will I use poly over epoxy. Having a board that will just bounce off the concrete is well worth the extra work.
Hello Halycon,
I’ve used polyester to gloss over two epoxy boards, and also use polyester exclusively for all repairs on epoxy boards. I use basically the same techniques for the application.
As for compatibility, I have not had any issues what so ever. Don’t the ‘chemical bond’ and ‘mechanical bond’ theories get misrepresented? I may be mistaken, but isn’t the following more accurate:
<ul class="bb-list" style="list-style-type:circle;"> <li>Chemical Bond: A layer of any resin is applied, and before it is fully cured, another layer of the same type of resin is placed over top, and they cure together creating a chemical bond between.</li> </ul>
· Mechanical Bond: Once a layer of resin has cured, the chemical reactions have stopped. Regardless if you’re putting the same type of resin on top or a different type, you’re only creating a mechanical bond not matter.
As for durability - I mainly use any final coats for aesthetic reasons, so in my mind, either choice is more than adequate for that task at hand.
Cosmetically, I do get my epoxy boards to shine well enough. But in contrast, polyester does polish out a whole lot easier and more brilliantly.
Best,
Herb Bean
Poly will physically bond to epoxy ( if abraded and no amine blush present), epoxy will not stick to fresh poly, until all the styrene has blown out. On cured poly you will also get a physical bond, but epoxy will stick better as it is a more aggressive glue. ( I am no chemist, but just my 2 cents).
Cheers
Mark
Howzit roostersurf, I’ve seen boards with poly hotcoats over epoxy literally pop off areas of the poly just from the board flexing to much. One reason some people use the poly over epoxy is because it makes sanding the board easier but the reallity is you should use epoxy for the hotcoat to prevent this.Aloha,Kokua
We actually did this for a few years. The disadvantages are
-
the polyester chips. This gets worse as the board ages. 2. The polyester actually yellows faster than the epoxy Anywhere the polyester is thin from sanding the board ends up staying whiter and the board ends up splochy.
-
The polyester is weaker and the board dents and dings easier with a poly hot coat.
There used to real advantages in the work place for polyester hot coating and finishes were cleaner. In fact, it was common practice in FL. Additive F and faster hardener speeds made sanding and hotcoating so much easier with epoxy that today I don’t know anyone who hot coats with poly anymore.
Epoxy Pro/XTR used to hotcoat with poly. I didn’t even realize the extent of the poly yellowing (and brittling) until someone bailed off their board right in front of me & I ran it over. I found a long chipped ding under the nose of my board - 12" long x 1" wide and all chipped & ragged on the edges - where the (epoxy) lamination coat underneath was still perfectly solid and still brilliant white! So…older epoxy boards that had a reputation for yellowing…its probably not the EPS or the epoxy, but the poly over the top.
On the plus side, it was easy to fix.