Halfords fiberglass resin

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haydude

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I was in a hurry and I purchased fiberglass resin from Halfords instead of driving miles to the nearest boat GRP supplier. To my surprise the methil ethyl ketone peroxide catalyst I had is like fresh water to the Halfords' resin which requires its own catalyst to set.

Is that Halford resin usable for my boat or have I wasted my money?
 
I prep'd everything properly, mixed it in the right ratios, yet after a year or so it started delaminating. Its odd that the isopon stuff is a yellow'ish colour yet the stuff I get from the GRP suppliers is totally clear.
 
The Halfords stuff is polyester resin I think, which is much weaker in terms of tensile strength and compression strength than epoxy resin. I would always use epoxy on a boat for pretty much all applications it is a much superior material to polyester.
 
haydude said:
Yes, yellow tin. Why not? Compatibility? Strength?
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Halfords now seem to sell Davids Fastglass ... I have a tin in front of me although in the past IIRC they sold Plastic Padding resin.
It will be quite suitable for your needs, although it is slightly pink

The hardener for the Fastglass resin contains dibenzoyl peroxide. It is a red paste supplied in a sachet packed in a small box which matches the tin of resin.

I would recommend that you use the correct hardener, especially for anything important, and to mix as closely as possible in the "correct" proportions.

The hardener you have may well work but I would not like to guarantee it.
I know of a major industrial fibre-glassing job that failed after a short time in service because the wrong hardener was used.

Plastic padding resin would be equally suitable. its hardener is a yellow paste which also contains dibenzoyl peroxide
 
samwise said:
The Halfords stuff is polyester resin I think, which is much weaker in terms of tensile strength and compression strength than epoxy resin. I would always use epoxy on a boat for pretty much all applications it is a much superior material to polyester.
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Most GRP boats use polyester resin in their manufacture - mine certainly did and has managed 43 years without incident. Just because something new arrives doesn't mean that the old is immediately useless!
 
lustyd said:
Most GRP boats use polyester resin in their manufacture - mine certainly did and has managed 43 years without incident. Just because something new arrives doesn't mean that the old is immediately useless!
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I tend to use polyester on all solely fiberglass applications, Cheaper, easier to use, not as temperature dependent. Also i think i read that epoxy is only stronger if it is post cured (open to corrections - i think it was Hugo du Plessis).
 
VicS said:
The hardener for the Fastglass resin contains dibenzoyl peroxide. It is a red paste supplied in a sachet packed in a small box which matches the tin of resin.
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It's normally red, as you say - if you shop around it IS possible to buy tubes of clear dibenzoyl peroxide, but not only is it harder to source, but it's a lot harder to judge when the goop is properly mixed.
The reason I bought some is that Isopon P45 is an almost perfect match (being a light cream colour) for touching up my decks and cabin, but pink isn't !
 
wklein said:
I tend to use polyester on all solely fiberglass applications, Cheaper, easier to use, not as temperature dependent. Also i think i read that epoxy is only stronger if it is post cured (open to corrections - i think it was Hugo du Plessis).
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The argument in favour of using epoxy is that is a better adhesive than polyester resin.

On a new lay up that is not fully cured polyester stands some chance of making chemical bond but on an old moulding you are purely relying on the adhesive properties.

For most/many purposes polyester will be adequate but where a really strong bond with the exiting structure is required epoxy is the better choice.
 
electrosys said:
Here's a very good article comparing epoxy with polyester:
http://www.hanseklubben.se/commonfiles/files/98.pdf
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I am pleased to read the very last paragraph of that article.
I have a "repair" to do below the waterline. I Intend using Epoxy although I have never used it before. Strength of the bond with the existing hull moulding is one consideration but resistance to osmosis without a gel coat is another.
 
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