Polyester Resin - Leftover puck cured on outside but "rubbery" on the inside

[Fastrack]

Polyester Resin - Leftover puck cured on outside but "rubbery" on the inside

Hey.

I did all my prep work because of a hole in my boat from a railway bunk collapsing. I've finished the entire layup of CSM & 1708.
http://forums.iboats.com/forum/boat...-hole-in-bottom-of-boat-from-bunks-collapsing

I phoned Noah's and the guy there said it's because it's UNWAXED resin, but I have my doubts as it's super tough on the outside yet rubbery on the inside. So that makes zero sense.

Anyway. I think I messed up something. Either not enough mixing? Not enough Catalyst? Too high humidity? I dono. I did not have this issue back in 2011 when I rebuilt a transom and a floor but it was less humid that's for sure, but colder air temp.

- 72F Air temp (62% humidity)
- Mixed 4oz or so at a time @ 1.5% (according to instructions 15 min working time, 45 min gel @ 68F)

The first CSM inside layer was still flexible after 2hrs, so I checked the hull temp and it was only 62F! So I heated the outside with a 500W halogen 2' away 30m later it had kicked off and I removed the tape.

I started to do the outside but because of the 500W heat it was kicking off too quickly. I stupidly reduced to 1.25% and turned the halogen off. And it dropped to 60F that night. It was still VERY sticky the next morning, I applied a 2% batch with air-dry and that kicked off.

NOTE: I decided to try sanding the outside with 40 grit disc wheel on a drill and 60 grit on a palm sander. No sanding issues or clogging of the paper.

I have no idea if or how I could even redo this, the outside I could use the grinder, but the inside is a very small opening and I've glassed almost to the edges. But being this is structural and a HOLE in the bottom. I'm VERY worried.

Rubbery "pucks" left in mixing cups:

I was only mixing small portions (4oz or so at a time). It seemed to gel in the "pot" okay, but the pucks are hard on the outside and throwing them VERY hard on the ground just cracks them. The inside is like rubber! Even hitting with a hammer just bounces off. I can "push" the bottom of the puck like a superball.

The only batch that has a pretty tough puck is the one I used 2% and Air Dry in!

The only way I could break the piece apart was to squeeze it in the vice and it DID NOT shatter it just "fell apart".

After hitting with a hammer: You can see the outside has fractured. But the inside I can easily stick a screwdriver into and peel it apart like rubber.



Breaking piece apart in a vice:


Ben

 

[kcassells]

I would say it was the mix not completely done at the bottom of the cup.

 

[Fastrack]

No one else?! Not a mixing issue, at least I don't think so.. See the following test samples.. ??


I've been worrying about this for over a week, with nice sunny days I could've finished my boat by now But I can't let this soft resin go. It's driving me crazy (maybe because it's a hole in my boat).

It was 71F in my cottage with 58% humidity. I decided to do another "test". I should've just bought Epoxy Thee instructions that came with it say at 68F do 1.5% is 15-20 minutes working time and 45 minute gel time. The printed label on the can says 15 min working time at 70F to 1%. I asked them and no one knows why it's different.

I found on wiki under Polyester Resin " Excessive catalyst may also cause the product to fracture or form a rubbery material."

So I did a 2oz batch at 8:30pm @ 1.5% and I stirred that sucker for 2 minutes, it had gelled by 9pm. The top had this rubbery feeling last night around 1am.
** I'm thinking the pot life of 30 minutes seems excessive and maybe pointing to possible MEKP issue?!@# Bloody h*ll I'm so worried. The MEKP has been in the boat for 3 weeks (it has a top and a tarp covering the windows, but it was getting up to 130F some days). The resin I always brought up to the cottage at night.

FYI - I'm measuring the Catalyst (cc) with a syringe from a vet clinic, so I know it's correct per the chart.

I did try sanding one of the pieces and it does sand, without clogging but the paper "drags" more, so the fact I can sand the boat is not good in my opinion.

This morning 12hrs later I did this test, yes the 1/2" hex nut can sink right in and it pops back up! This is not a trick. Pressing hard split it. The inside is the 3rd photo and the ONLY rock hard part is the shiny outside. Strange enough even though it's waxed it's not sticky at all!

The instructions also say "Batches less than 2oz might not cure" could this be why?! The 6oz left from my 12oz batch looked like this, the shiny middle was rock hard and the outside layer was like above. Now these batches I did not stir like a crazy horse so it's not a direct comparison.

Ben

 

[Woodonglass]

Polyester Resin and MEKP Both have shelf Life you don't know how old itis when you buy it IMHO you have OLD resin and MEKP You should always ask dealer how long they have had it before buying

 

[Fastrack]

Polyester Resin and MEKP Both have shelf Life you don't know how old itis when you buy it IMHO you have OLD resin and MEKP You should always ask dealer how long they have had it before buying

I've been loosing my mind over this since I noticed it. I guess this is the reason to make a test batch. Could this be related to a "small batch" like 4oz batches?

The issue is the laminations seem rock hard. I've sanded it and it seems okay, however I tried sanding some rubber stuff by hand and though the paper "drags" it does sand!. But this really has me worried.

I phoned the place where I bought and he said "the oldest it would be is March". As they order it in 55 gallon drums from Interplastics in the US. However the can I bought has no batch code on (and it should.. it's a sticker they put on it, when they dispensed it). The MEKP has a batch code of 0317, but of course that's when they dispensed it not sure how old the source is. They claim they go through a Drum every month, but that doesn't add up. If I bought this May 12th, and they dispensed it in March that's 2 months

I took the puck to a local guy who rebuilds boats for a living. He said "wow it shouldn't be like that, your lucky it cured that much". He proceeded to agree with what your saying that it was old resin or mekp?!@# But then he says "Hit the stuff on the boat with a hammer and see if it's hard". If it is just leave it. He also said sometimes resin behaves differently when you wet out the mat.

So I dono what to do !

He orders from Composites Canada. He said he's never had an issue - made by AOC. https://www.compositescanada.com/pro...r-resin-480-gp

Ben

 

[gm280]

Fastrack, I've been following your thread and reading you problems. Not being there and seeing how you are mixing your batches, or the weather you are mixing them in, I can't say it is bad resin, MEKP or anything else.

I do remember my first batch of polyester and MEKP. I mixed it exactly to the provided instructions and it took days for it to harden and cure. But since that time, I have never had another suspect batch again. And a lot of those batches came out of the exact same 5 gallon pail as well. I will say I went completely to metric measurement and not only is it easier to mix, it is quicker as well.

I bought mixing cups from a local automotive paint shop and they have both metric measurement and ounces on each mixing cup as well. But I use purely metric measurements and have never experienced any problems. And I can tell you, I've mixed up some very old poly and MEKP without any issues. And when I say very old, I am talking over a year or more.

I will say I do mix for at least two minutes. I actually watch a clock on the wall and use that minute hand as my go by. So maybe you are thinking you are mixing long enough, buy in realistic terms, not the two minutes they state. IDK

I would mix up a small test batch with at least a 1% or more MEKP and mix for at least two minutes and see how that kicks off and sets up. A great measuring tool I use for my MEKP is this. It has markings on it so you can easily pour the exact amounts you need and no need to use other mixing cups. I bought it shortly after starting my boat refurbishing project because I knew I was going to be mixing lots of polyester batches for a long time. Well worth the money.



The metric markings on the tube is easy to squeeze the bottle to fill up to the amount you need. Then you just pour it into the polyester and start mixing. Works great and so easy to work with and hold your MEKP without getting contaminated. JMHO

 

[Fastrack]

I bought mixing cups from a local automotive paint shop and they have both metric measurement and ounces on each mixing cup as well. But I use purely metric measurements and have never experienced any problems. And I can tell you, I've mixed up some very old poly and MEKP without any issues. And when I say very old, I am talking over a year or more.

I will say I do mix for at least two minutes. I actually watch a clock on the wall and use that minute hand as my go by. So maybe you are thinking you are mixing long enough, buy in realistic terms, not the two minutes they state. IDK

This is not a double post. But my images from above have disappeared.

I do understand what your saying, about measuring and I started with "drops" for the stuff on the boat. Pain in the butt, but all my tests since have been using a syringe from a vet clinic. So it was not related to the drip method. The resin for the boat I might not have mixed for more than 30 seconds, but all the tests since I've timed it for 2 minutes. Same result.

I'm using Measuring cups with OZ markings on them from the supplier, these are not weights. To measure the cataylst I'm using a syringe from a vet clinic.

The only batch that is ROCK hard is/was the batch for the inside it was 12oz with about 6oz left, which I might have under stirred, but I used the drip method into a cup. It was rock hard on the inside and rubbery on the outside.


----------------------------- Previous post with photos ----------------
This test was done at 71F in my cottage with 58% humidity. The instructions that came with it say at 68F do 1.5% is 15-20 minutes working time and 45 minute gel time. The printed label on the can says 15 min working time at 70F to 1%. I asked them and no one knows why it's different.

Mixed at 8:30pm @ 1.5% and I stirred for a timed 2 minutes, it had gelled by 9pm. By the next morning it was still kinda rubbery throughout (see photos). It's now 3 days later and it's STILL rubbery!

This test was done the morning after (12hours later or so).

The 1/2" hex nut can sinks right in and it pops back up! This is not a trick. Pressing hard split it. The inside is the 3rd photo and the ONLY rock hard part is the shiny outside. Strange enough even though it's waxed it's not sticky at all!



-------------------------------------------------------------------------

I've also at the advice of someone else soaked the area with Acetone for 1 minute, I could not feel any softness. BUT I was able to scrape off the resin with my fingernail! So something is not right.

https://youtu.be/Ox5xh27WUQw

At this point I'm looking into a different supplier, I dono what else to do. The instructions do say "small batches less than 2oz might not cure".

Ben

 

[gm280]

I read your additional posts and the only thing that makes me scratch my head is you did have one batch get rock hard. That tells me that it does kick off correctly. But why it doesn't with small mixtures doesn't make any sense. I would certainly buy NEW poly AND MEKP and try a SMALL batch first to see. If that doesn't harden, then you have to be doing something different then the usual. If it does kick off and hardens then you had some suspect poly and/or MEKP. JMHO

 

[mxcobra]

I didn't read through all the post so forgive my if I misunderstand , to me it looks like you are testing just the resin with no glass in it. if that is the case then the results from the picture are correct. Its the fibers from the glass that hold the resin together if that makes sense. also I have found bellow 65 70 degrees. in low humidity like here in Colorado. It take more like 3 percent to get a good cure and never really fully cures untill the outside temps reach above 70 more like 80 DEG

 

[Fastrack]

I read your additional posts and the only thing that makes me scratch my head is you did have one batch get rock hard. That tells me that it does kick off correctly. But why it doesn't with small mixtures doesn't make any sense. I would certainly buy NEW poly AND MEKP and try a SMALL batch first to see. If that doesn't harden, then you have to be doing something different then the usual. If it does kick off and hardens then you had some suspect poly and/or MEKP. JMHO

I've placed an order for some new resin made by Altek AOC H596. From another company in Toronto called Plastic World he said the products on the shelf cycle every week. So they go through a ton of this stock.

I didn't read through all the post so forgive my if I misunderstand , to me it looks like you are testing just the resin with no glass in it. if that is the case then the results from the picture are correct. Its the fibers from the glass that hold the resin together if that makes sense. also I have found bellow 65 70 degrees. in low humidity like here in Colorado. It take more like 3 percent to get a good cure and never really fully cures untill the outside temps reach above 70 more like 80 DEG

Yes you are correct. I'm not testing the strength, I was trying to show the rubbery nature of what I was seeing, which is VERY hard to describe unless you can hold the piece in your hand.

---------------
This is my last test with this resin as resin and or the hardener is suspect. But for those interested:

I spoke with Dave H. from Interplastics the people who make the resin, he is also the director of R&D.

He just published this article, that explains the curing of Polyester resin:
http://compositesmanufacturingmagazi...-applications/

He said the resin is under-catalyzed or something weird with the Resin (ie the drum had moisture in it etc..)

The large batch I made is the only one to have hardened, although it had a rubbery outside? Which I suspected was mixing issues but with all my tests since it's become obvious that's not the case. I remember it being around 285F when it was curing.. So maybe it drove the moisture out of the resin?!@#

He said to try a test batch at 2% and see what happens. So I did that today.

4oz in a 6oz cup
- Resin / Surface / Air Temp 74F
- 2 min mix (timed)
- 3% Air Dry (3.5cc) - just so I didn't have sticky test pieces.
- 2% MEKP (2.5cc)
- On wax paper I poured out a small circle about 4" in diameter, and wet out some 1708. The leftover was 3oz.
- Gelled 16 min @ 100F
- 236F @ 24 min - Dave said a portion like this @ 2% he would expect to hit 350F range. It turned quite dark at this temp... but then lightened up.
- 95F @ 110 min

By 150 min it was around 84F. By that time Dave said it should be hard, once the reaction is over the material is "done". Not at the final hardness, but shouldn't be "rubbery" like I'm seeing.

It's 5 hours later and the puck is still rubbery.

At 236F:

The piece that is resin only can be curved using an elastic band without breaking (just over 1/16"). I did manage to shatter parts of it, but about half of it is "VERY flexible" and doesn't shatter like the rest. The 1708 is a tough call cause the material itself is so strong when wet out. It makes a cracking sound when folded almost completely in half and does crack.


Thank you all for your help. I just hope this helps someone else.

I will be doing a small batch test with the new Resin when it arrives.

Moral of the story - Do a bloody test batch. I figured why bother? I've used Poly before - no need. How wrong was I.

Let the grinding begin, damn it.

Ben

 

[gm280]

Yea, there has to be something wrong with the materials.

I can tell you, any amounts I have left over, and that isn't usually the case when I do a batch, it hardens so hard, you can bang it on the bench and it is like a hammer. I have now mixed well over 20 gallons of 435 laminating resin and every batch did what it was supposed to do. I bought all my supplies from U S Composites out of Florida. Good company and the cheapest cost. Well for me anyways. JMHO

Do come back and let us know what your new poly does. I'l like to know.

 

[Woodonglass]

Bad MEKP or Bad Resin. HAS to be!!!

 

[Fastrack]

Yea, there has to be something wrong with the materials.

I can tell you, any amounts I have left over, and that isn't usually the case when I do a batch, it hardens so hard, you can bang it on the bench and it is like a hammer. I have now mixed well over 20 gallons of 435 laminating resin and every batch did what it was supposed to do. I bought all my supplies from U S Composites out of Florida. Good company and the cheapest cost. Well for me anyways. JMHO

Do come back and let us know what your new poly does. I'l like to know.

Yeah, that's what I kinda figured back in 2011 with my transom rebuild I vaguely remember having couple of blocks and they weren't like this. However I was wetting out much larger sections so the likely hood of having any leftover was slim.

Bad MEKP or Bad Resin. HAS to be!!!

100% I've done more tests than a company that makes this stuff.. HAhA

I haven't ordered yet I almost submitted the order though. My plan last fall was to use Epoxy by System Three (Silver Tip). But I wasn't sure if the glass would stay in place laminating above my head.

I spoke to the tech person at AOC. She said Altek H596 (Othophthalic) is general purpose and is great for tabbing in stringers or transom rebuilds etc.. But because this is below the waterline she wouldn't use it. She suggested a Vinylester Resin which this place also sells ($69/gallon vs $49/gallon). I doubt I need a gallon but a pint is $24 so bah. I have a call into the reseller to see what AOC line the vinylester is.

My plan in my other thread was to coat the repair with my Interlux Micron CSC bottom paint and that still is the plan.

Ben

 

[Fastrack]

Well. I decided just to order the general purpose. It's an old boat, and the original boat probably didn't have a "Barrier coat" back in 1988 And if I had this repaired locally the guy here uses H596, the same resin I just ordered.

I'll update the thread once I execute some new tests.> HEHE

Woodonglass - You followed my original thread (http://forums.iboats.com/forum/boat...-hole-in-bottom-of-boat-from-bunks-collapsing). Any idea how I can get back to the original surface? Or should I just get down to the first layer, my problem is making this a much larger hole I'm pretty good with the grinder though

Ben

 

[Fastrack]

Well I figure the resin is going in the trash or the MEKP. So I decided to do another test batch. HAHA. My new resin should be here tomorrow.

All the same conditions, 3% Air Dry and around the same temp too. The 3% MEKP one got up to 268F and was very dark.

2% broken in half with a 3" cold chisel. It's glass hard except the top 5/16" is rubbery, the outer edge is also suspect!


The 3% is the best so far, the outer edges actually broke off and seem glass hard, but the top is still rubbery less though maybe 3/16".


I'm planning on doing another test using the new MEKP and old resin. And of course a test with new materials

Ben

 

[Fastrack]

Hey all,

So the new resin arrived. Plastic World was great to deal with, the ordering guy knew all about the shelf life etc. The current Poly they sell is AOC Altek H596 unwaxed and waxed and harder is Norax MEKP-925H (9% Active Oxygen). They also sell Vinylester too.

I also spoke to AOC and the person said generally 1.25% (77F) is the best and really no reason to go over 2% (ondarvr on here said something similar).

I of course did a test yesterday:
Air Temp: 73F
Batch: 100ml (3.38oz), in a large 1 quart and also in the small 6oz
Mekp: 1.5%
Air Dry: 3%
Mix time: 2 min
Gel time: 13 min large bucket, 10 minute small 6oz

Based on the gel time, I think I could so 1.25% at this temp.

The small cup got quite a bit hotter as it was a larger "mass", which was expected. You can see the small puck below is darker because of the smaller mass.

This resin is a nice light blue colour too, so it's easy to see the colour change with the MEKP. The other stuff was dark green so it just got a "bit darker". If you watch BoatWorks Today, he said the resin should change colour in about 15 seconds (and it did). The old resin took at least 30 seconds to do that (unless it was just hard to see).

OLD Resin Test with new MEKP: Still like rubber even this morning. I'm not using the old Mekp as I don't need it, but it was probably okay. But the new stuff smells WAY different.

The conclusion is... RESIN was defective!. The new stuff when hit with a hammer flew everywhere and is hard like glass throughout. MUCH harder to smash the small puck though.

I also wet out 1708 but no need to post those photos. (I couldn't find all the piece of the large puck.. haha)

FYI: Once the puck cooled to room temp, it was ROCK hard. The break test was done about 4hrs later though.




Ben

 

[gm280]

Well glad you got it all figure out now. I like using poly and never had any issue with it. But I buy from US Composite out of Florida, since I live in Georgia. They do a huge amount of business and therefore, I don't see how you could get any suspect resin from them. Too much turn over for it to set on a shelf. And they ship fast and their prices are the best for me. JMHO

 

[Fastrack]

Well glad you got it all figure out now. I like using poly and never had any issue with it. But I buy from US Composite out of Florida, since I live in Georgia. They do a huge amount of business and therefore, I don't see how you could get any suspect resin from them. Too much turn over for it to set on a shelf. And they ship fast and their prices are the best for me. JMHO

Yeah I agree 100%. The ordering guy at the place I bought from this time, said the stuff on the shelve lasts about a week So they have a huge turn over! Dave the R&D guy at the other resin place said he figures moisture got into the drum.

Lesson learned -- Do a test batch or two before hand, man alive I would saved myself A LOT of time!

I do appreciate the feedback from everyone, now to start the grinding process, oh what fun!

Ben

 

[gm280]

Yeah I agree 100%. The ordering guy at the place I bought from this time, said the stuff on the shelve lasts about a week So they have a huge turn over! Dave the R&D guy at the other resin place said he figures moisture got into the drum.

Lesson learned -- Do a test batch or two before hand, man alive I would saved myself A LOT of time!

I do appreciate the feedback from everyone, now to start the grinding process, oh what fun!

Ben

I think grinding fiberglass is a way to separate those that are truly wanting to refurbish their boats and those that don't. Otherwise who would do such tasks. You seriously have to be dedicated to your boat to go through all that grinding. But the feeling is awesome when you finish that portion of it.

You know the rule, Fastrack, it didn't happen without pictures. So grind and post away. :thumb:

 

[Fastrack]

I think grinding fiberglass is a way to separate those that are truly wanting to refurbish their boats and those that don't. Otherwise who would do such tasks. You seriously have to be dedicated to your boat to go through all that grinding. But the feeling is awesome when you finish that portion of it.

You know the rule, Fastrack, it didn't happen without pictures. So grind and post away. :thumb:

Trust it happened once already, and onto Round Two! No way I was leaving the defective laminated resin layers, I had no idea how strong it was.

I do have some questions, as I made my hole bigger than expected. If you can jump over to the other thread
http://forums.iboats.com/forum/boat...from-bunks-collapsing?p=10426987#post10426987

Ben