What's This ? is it amine blush?

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alick burt
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What's This ? is it amine blush?

Post by alick burt »

Hello folks
I ahve made a few canoes now and sometimes have this when I reach sanding stage after glassing.My resin has been left 2 weeks and I have scraped and sanded it and I have left it alone whilst fitting gunwales.
As you can see in the picture there is an area that looks to me like perhaps the border between coats of resin where one has been almost sanded off an earlier one?? or is it perhaps amine blush.
I sanded after a week of setting and the resin was all applied same day in four coats with about 2.5 to 3 hrs between coats.
I generally sand dry after scraping off runs but if this is amine blush I guess I have to wash it and perhaps wet sand it off.
Many Thanks
Alick
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Cruiser
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Re: What's This ? is it amine blush?

Post by Cruiser »

Hi Alick,

I thought amine blush was more of a film, like soap film on a window ... what you have there seems to have a lot more "physicality". Almost like the final coat of resin didn't adhere in that locale .... as you pointed out, amine blush is washed away, not sanded and that pic doesn't look like blush.

Just my opinion.


Brian
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Jim Dodd
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Re: What's This ? is it amine blush?

Post by Jim Dodd »

Hi AlicK

A few questions. First what resin ?
Temps during the time of cure ?
Was the resin properly mixed ?

Is this wide spread, or just in one small area ?

Sorry ! more than a few questions !

I apply my resin in much the same time schedule, and haven't had this trouble.
Blus has been more of a problem with varnish sticking to the hull.
Curious !

Jim
Keep your paddle wet and your seat dry!
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Jim Dodd
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Re: What's This ? is it amine blush?

Post by Jim Dodd »

Another question. Any contaminants floating around the air ? Solvents and the like ?
Oh! Method of application also ?


Jim
Keep your paddle wet and your seat dry!
alick burt
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Re: What's This ? is it amine blush?

Post by alick burt »

Hi Jim and Brian
Thank you for your replies.
Resin is from uk epoxy.I have used it a lot and had this happen before.I think I remember it disapppearing when I varnish but I have also had varnish drying problems in the past and that may have been on the boats that had this effect. I know it would make sense to ask my supplier and I know he will give me an answer but I also know he favours not varnishing until the boat has been used for a month or so but of course I cant be doing that with boats that are for customers!
All resin was applied at 17 degrees C.( I warmed the workshop to that in the morning then kept it constant until I left when it would have slowly dropped.Workshop is insulated so it would have taken a while to get down to the outside temp which was 10 by morning outside.
Mixing was for a full 2 mins per 4 pumps per cup.(about a third of a pint)
It is wide spread and does look like a layer change of some sort unless it is something else on the surface which made me think it might be blush.
I dont think anything was contaminated my brushes were all new and containers too.
Application was by squeegee on the flat area of the bottom and down the sides>I tend to spread v gently with squeegy as much as i can only resorting to brushes on vertical areas.
Any more thoughts comments welcome.
Many Thanks
Alick
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Cruiser
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Re: What's This ? is it amine blush?

Post by Cruiser »

Hi Alick,

Does the manufacturer have recommended temps for curing, those temps you are quoting seem like they may be a bit low to get consistent/reliable cures .... temp has a big impact for epoxy.

I have used it successfully at those temps, but I have also had some bad results at those temps. Higher temps around 20C have never given me issues.


Brian
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Jim Dodd
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Re: What's This ? is it amine blush?

Post by Jim Dodd »

Using a hull a month before varnishing, spells Blush to me !

I'd look for another supplier ! I've not had blush problems for Way back !
Your application doesn't sound bad.

I've always had the best luck in the hottest weather, applying epoxy. I would keep the shop warm for at least 24 hr if possible !

Good Luck Alick !!!

Jim
Keep your paddle wet and your seat dry!
sedges
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maybe contaminated cloth?

Post by sedges »

The pattern looks like the weave of the cloth. It is possible the cloth is contaminated. Handling glass cloth can transfer oils from skin or sweat. It can also come from the supplier with contaminates in the finish or inconsistently finished cloth. I am always cautious about cheaply priced cloth. Sometimes it is good cloth that happens to be overstocked and needed to move, but sometimes it is seconds, often due to chemical finish issues.
alick burt
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Re: What's This ? is it amine blush?

Post by alick burt »

Hi Folks
Thank you for your replies.I was scraping and sanding the insides today and I have come to the conclusion it is definately the two applications of resin where i have sanded off a bit of the last one.It is nearly two weeks since I applied it and in think it may still be,a little soft in places.This,tends to be where the resin is thinnest (on the verticals ). On the bottom where the resin is thicker there is no sign of the problem.I think if I leave it,a bit longer over the weekend it will be fine.
I was also told and it is in the instructions that it can be applied as.low,as 10 degrees and 17 is fine.
Thank you for your answers they helped me eliminate,what it wasn't.
Please forgive any typos my laptop crashed so this is on my mobile!
Many Thanks
Alick
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Jim Dodd
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Re: What's This ? is it amine blush?

Post by Jim Dodd »

I would shy away from pumps to accurately dispense resin !
I use cups. Some use digital scales and are happy with them .
Pumps burp and give inconsistent amounts !

Jim
Keep your paddle wet and your seat dry!
sedges
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one more thought on this

Post by sedges »

Early on in my boat building experience I re-used mixing containers as I was glassing. The mixed resin that was left coating the sides and bottom of the container seemed to mix in fine with the new resin. The problems began appearing as I squeegeed the excess resin out of the cloth. Patches of resin had gotten a little tacky and air became en-trained that I could not get out. The result was not pretty. I learned my lesson well and always have a stack of mixing containers handy. Even if the was mixed 15 minutes earlier, it is not going to mix well into fresh resin.

Alick! Did you re-use containers as you glassed?
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