I have a block of EPS, probably 1 pound density but not sure. It’s from the stern of Manoa’s fish board, he gave it to me when I went over to check out the things he was doing.
It has been sitting around a good few months, outside, but not much in sun. It’s felt rain, sun, and wind.
I had at it with my short surform the other day, the blade though not new was fairly sharp I thought. The EPS cut easily, but with any pressure I’d start ripping out “cells” of it, leaving a very rough surface. H’m. I tried a bit of 60 grit and same thing. Light pressure left a moderately rough surface, but any pressure would rip the surface fairly badly.
Now I have to know:
Is this typical of EPS, or am I just working in the weathered zone? I went about half an inch deep, and no change in the effect. Light pressure so-so finish, heavy pressure and rip it all up.
Is this why a layer of spackle is often noted as a key pre-glassing step, no one takes time (or it’s impossible) to finely finish an EPS blank?
Do the heavier weight EPS densities do the same thing?
I gotta talk to some EPS shaper/glassers. I ran into Mark Jackola the other day, he says he has been doing a bunch of EPS/epoxy stand up paddle boards around 14 feet with double half inch balsa stringers. H’m.
Charlie, spackle it. Lightweight spackle mixed with water, bondo spreader. Use your hands to get the rails and squeegee it all off. Let dry overnight (or over a week in this weather). Screen/sand. Do it twice to get it really nice. Also if it’s 1#, you’ll have to spackle it to keep it from draining when you lam anyway. I put em in my hotbox and they dry fast. Make sure the blank is super clean before spackling or all the stains and dirt really show up and don’t ever come out once you get the blank wet. I’ve been doing a ton of em lately.
Is this typical of EPS, or am I just working in the weathered zone? I went about half an inch deep, and no change in the effect. Light pressure so-so finish, heavy pressure and rip it all up.
With 1# density it is common.
Although there are newer EPS foams made with better fused beads and shape well even at lower densities. Markofoam is one and Segways American Blanks is another example
Quote:
Is this why a layer of spackle is often noted as a key pre-glassing step, no one takes time (or it’s impossible) to finely finish an EPS blank?
Spackle is so the resin doesnt drain into the blank. you can get a decent finish
Quote:
Do the heavier weight EPS densities do the same thing?
No higher densities and better fused beads. Higher densities dont need spackle unless your doing color work
I guess: it’s not such good foam (Manoa overlaid his fishing board with Dcell, epoxy and that yellow POR-15 Hardnose); I need to get/use better quality EPS (haven’t actually done an EPS yet); I need heavier weight foam (was thinking that anyway, just tried to tool the scrap on hand).
BamBam, no time no see! Last we spoke, seems you were all about “PU is the only thing and all that will ever be” … the wheel turns. Helluva nice morning on Wednesday at the usual place until the brown water came in and wind switched to southeast.
J Troy I will phone and we can talk, when I corral some materials. Ever the scrounger, my brother in Hilo has a couple gallons FH 4:1 that I will probably acquire and use, perhaps on some 2#, if I can source that. No rush; in the meantime FH has PU blanks coming next week and several other shipments thereafter.
Meanwhile I dream and consider the relative properties and uses of various materials. I share office space with a structural engineer who surfs or used to; I made/sold him a couple boards; he occasionally uses heavy woven carbon roving and epoxy to reinforce old buildings which don’t meet modern building code requirements for shear.
long time no chat. I’m currently shaping another fishing board, this time the board will be made with 2.4lb density.
no high density foam wrap, just plain old fiberglass and epoxy resin. You can buy block “billets” of 2 or 2.4lb density from Pacific Allied. Keep in mind…that it may take time to get your order in. my hotwire setup cuts 2.4lb ok, not as fast as cutting 1lb.