Does anyone know the name of the little roller device That has dull little Needle like protrusions that cause little depressions Into the blank so the resin can form, “roots” so the fiberglass will better adhere to the blank. I thought it had pickle in the name. (And where to buy one.)
I can’t tell you the name, but original intended use was for leather work. Used to make indentations on leather. Try a google for “leatherwork tools”. Found it ; “leather tracing tool”. Temu leather tools.
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There is the aircraft Porcupine Roller but it is pricey.
The Wartenberg Neurological Roller is an affordable alternative I like. You want the “neurological tool” not the erotic toy.
Critical factors for XPS perforation are:
* Pin diameter
* Number of pin rows per inch
* Number of pins per wheel/row.
* Roller diameter and pin length
The more small diameter holes the roller makes per square inch, the better.
The 7-row Wartenberg rollers (22 pins/wheel) I have make 44 perforations per square inch. Pinwheel diameter, pin-tip to pin-tip, is 1.125" (28.6 mm). Roller width is 1" (25.4 mm), pin-tip to pin-tip. Pin length is approx. 5-6 mm. Perforation hole diameter at the foam surface is approx. 1 mm. Space between perforation holes is approx. 4-5 mm.
XPS perforated with 7-row Wartenberg pinwheel roller (meaure = inches).
Aircraft Porcupine Roller
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Thank you Stoneburner, you’re the best!
Yeah I remember that one now. I am glad though that such a device isn’t necessary for the materials I use.
BTW You can pick up a Wartenberg on eBay. They have a 10 wheel roller too.
Aircraft Spruce carries a Pocupine Roller.
It’s not too bad.
Beats doing the old 40-60 grit final sand method. With the W-roller my final sand is 100 grit, vacuum, perforate, then squeegie on a thin epoxy pre-seal. (Upside is the pre-seal reduces amount of lam resin needed.)
xps wire brush sanding prep seems to work too for increase peel strengh. May be there is something to search about chemical too. PU glue stick so well to xps and epoxy so less…
I have considered water-based urethane as an XPS seal coat. But I’m not convinced that it will bond better with XPS than epoxy. Or that epoxy will bond better with water-based urethane better than XPS.
Do you have any suggestions for a simple to use, cost effective urethane/polyurethane finish to seal XPS with?
These two types of glue don’t mix well . You may get away with a dry coupling layer - short fibers in a well spread coat of glue. The Pu glues I know are more spackle consistency, and I think they won’t lay down nice and flat like epoxy does . This is a good way to bond stuff that otherwise doesn’t like to mix.
There a 2k PU breeds that don’t need water or moisture for cure . Those would be my premium choice.
I see that your interested in cork . I think a good option would be to glue the cork with 2k onto the XPS , and after cure proceed with epoxy .
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At seprate test, pu monocomposant glue, stick very well to prep xps. No separation, break xps. On other side very easy so separate when glue with epoxy. I am not an expert of pu resin but i know there is urethane resin used as matrix with fiber. Why pu glue better on xps ? Chemical? Or only because of higher elongation to break?
I’m guessing a surface energy value midway between XPS and epoxy.
So you should find a polyurethane resin for lam or at least a primer between foam and epoxy lam that improve bond. Old time we used a polyuethane primer on wood before polyester lam, call polyurethane G4
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Just from talking to a technician of a glue manufacturer -he basically said its both , better chemically and since the pu is not as stiff more forgiving to shear. its recommended to leave it thick -0.5mm or so, the stuff i have is sold with a v-notch trowel.
The problem is the PU adhesives are too thick to use as a surface penetrating coating.
Polystyrene (XPS & EPS) has a surface energy of 36-40. Epoxy has a surface energy of 39-47. Water-based spar urethanes have surface energy values between 30-45.
Ideally, you want them all to have the same surface energy value and a viscosity suitable for penetrating small pores, channels and perforations.
I don’t know how to use those numbers, but the recommendation is to sand 60 or 80 grid . In XPS there is no penetration or soaking in anyway because of the nature of the foam.
Depends on how you prep the foam surface. As with EPS, resin anchoring is the objective.
Bottom line, for coatings and adhesives, you want the surface energy values to be the same for the strongest bond.
The G4 PU primer is fluid like a wood varnish. We used it as a wood sealer and primer for polyester lam.
May be waterbased epoxy primer, that stay slightly flexible could work too for improve bond of a stiffer lam epoxy. Or use a wood multipurpose epoxy in general slightly more flexible (around 6-8% elongation) than surf epoxy (3-5%).
I try the brush wire prep of xps find on boat forum. Visualy give lot of “grip” need to test lam bond. I only use xps as center stringer to widen eps blanks for sup and windsurf now. In the past i try 2 full boards and a half dozen of xps rails. Homedepot 2lb thin cells xps, standard lam over 40-80 grit prep. All delam more or less quickly. I know guys build diy plane with large cells eps without problems, they says only use large cell xps (spider foam from Dow), can’t find it but i see it and looks “open surface ” like a sponge, no separation at peel test.
I believe Dow sold their XPS business to DuPont.
I have been looking for a suitable polyurethane seal coat. Have been considering testing this one.
https://ecosafetyproducts.com/ecopoly-polyurethane-sealer-finish/