Custom Fiberglass Extended Swim Platform

[tpenfield]

I have a bunch of stuff on order to test out for the gel time reduction.

Norax MCP catalyst - extends gel time to about 2X

TBC - can be used to extend gel time 2-4 times normal by using 200 - 500 ppm. Probably best to stay 300 ppm or less.

I plan on setting up an 8" x 18" test of 3 layers of 1.5 CSM this coming weekend to see how everything will work. I will probably thin the resin by 3-5%. If my stuff arrives, I will go with the inhibitor or the Norax catalyst (but not both).

Here is a diagram of the test, showing the layers of glass and vacuum infusion/bagging materials.

Here is the planned setup, which is typical of any VARTM . . .
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Here is what is supposed to happen during the infusion. . .
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I plan on having the vacuum line set up so that it pulls through the fiberglass. As the resin is introduced at one end, it should flow laterally along the flow media, then downward through the peel ply into the glass layers.

This setup is typical of what the resin travel will be when I make the swim platform mold. I will time the resin travel through the flow media and then see how well the CSM is saturated.

I had been using an online resin and glass calculator, but then I realized that the resin calculation was off. It was calculating as 100% resin and no glass. I assume for hand layup there might be 80% resin 20% glass, but for vacuum bagged infusion is should be more towards 50% / 50%. Initially, the calculator showed for 1 sq. ft. of 3 layer mat, it would be about 1/8" thick, and would use 10 oz of resin. Checking the calculations, I found that the entire volume would be 10 oz. . . . so the resin is really going to be about 1/2 that.

I plan on activating 6 oz of resin for the test.

When I applied the same logic to the entire platform (42 sq. ft. x 1/8" thickness) and factor it to 50%, I comes out to only 1.7 gallons of resin for the infusion of the platform mold. Seems low, but I'll check my calc's. Based on the hatches that I infused, it seems like I have been prepping too much resin, using this calculator, as I had about 50% wasted resin. I'll plan on prepping 2 gallons of resin for the platform mold, depending on how things go with the test.

I'll post updates this comping weekend.

 

[tpenfield]

Quick Update . . .

I have been wearing out my computer keyboard, searching for TBC or any other 'inhibitor' . I tried to get some from a few commercial suppliers, but no luck.

I finally came across some HQ (hydroquinone) and some TBC (4-tert-butylcatechol) at a retail level. I ordered some TBC, so hopefully, I will get some and can do some resin cure time testing at the 250 ppm range to see how well it works, both in extending the gel time and the results of the final cure.

The Norax MCP (slow catalyst) should be delivered on Friday, so I can try my VARTM test using the slow catalyst.

 

[kcassells]

THC ? That shouldn't be so hard to find. Check with zool I think he's up on his roof fillin holes today.

 

[Scott Danforth]

I think that is TBC, not THC..... pretty sure if Ted had THC.... he wouldnt be stressing....... then again, not sure the swim ladder would get done....

 

[tpenfield]

I think that is TBC, not THC..... pretty sure if Ted had THC.... he wouldnt be stressing....... then again, not sure the swim ladder would get done....

Exactly . . .

 

[tpenfield]

Slight change of plans for the weekend . . .

In addition to doing the resin flow/gel time testing, I will probably have some extra time on my hands. When I inspected the first hatch mold, it initially looked OK, but upon cleaning it, I realized that it had a few areas of resin void and the gelcoat was 'loose' and slightly perforated.

So, with the extra time that I should have, I'll repair the hatch plug that got damaged and take another run at making a better mold. Here is the plug after mold separation. . .
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The corners were torn apart and the base cracked when trying to separate the mold from the plug. I should be able to fix this plug and make a new mold.

 

[kcassells]

All is looking great!

 

[zool]

I would need THC just to monitor the resin migration.......

 

[tpenfield]

I was thinking I'd need THC in order to endure the struggle of finding TBC

 

[tpenfield]

Update - Feb 23, 2019 . . .

A big day doing some tests and working on the hatch molds.

Hatch Plug/Mold . .

I decided that the hatch plug was a bit too damaged to fix up this weekend. Sooo, I put some more time into re-working the mold from the damaged plug. Pictures to follow tomorrow

Resin cure test pitting MEKP vs MCP catalyst.

1/2 oz of polyester each and 2% hardner. The resin was 60 F degrees (cool) so I went with 2% hardner.

I mixed each up at the same time and poured the 1/2 oz out on a piece of plastic sheeting.

The poly/MEKP took about 60 minutes to gel in open air

The poly/MCP took about 120 minutes to gel in open air.

So, it looks like I am getting 2X with the MCP hardner.

Peel Ply . . .
I also tested the peel ply for how quickly liquid will flow through it . . . Not very quickly I used some water and it seems to really restrict the flow. So, I'm going to look into a different type of peel ply to see if I can get something a bit more porous.

VARTM Resin Flow Test . . .

I set up my test of VARTM on 3 layers of 1.5 oz CSM. Supposedly CSM does not flow resin very well, so this will be a good test as a 'worst case'.

I mixed up 6 oz of poly resin, thinned it with 5% styrene, then activated it with 2% MCP harder.

I set up the vacuum. I had a small air leak that I could not seem to get rid of, but managed to get 25 Hg.


If the CSM was getting saturated, I should see the area of CSM farthest to the right start to wet out. After 8 minutes, I did not see resin extending to the right.


Finally, at 30 minutes, the resin was flowing through the CSM to a point where it was showing on the right side.


At 45 minutes, it had fully saturated the CSM, which is a good sign.

At this point, (Saturday evening) the test piece is still under vacuum as it cures.

Key take-aways from the test.

-> The flow media works pretty well in dispersing the resin throughout the area.

-> As such, I was able to empty the 6 oz into the 'mold' within a minute. Therefore the resin did not have much time to build up heat in the resin pot. So, that will be my strategy for the main mold . . . get the resin to flow quickly into the vacuum bag. It should be do-able with an abundant amount of runners.

-> Sealing the inlet & outlet tubes is a bit tricky. I think I will use some Silicone II on the fitting/bag interface and let it set up overnight.

-> It looks like 60 F degrees is a bit on the cold side, so I will have to work on warming the garage a bit . . . maybe to 65 F. :noidea:

That's all for now . . .

 

[tpenfield]

Quick update regarding the test 'part' . . .

The test part had cured enough that I could turn off the vacuum and pull the part out of the bagging.

It looks like the outer 3" or so did not get a full saturation, so something to keep in mind for the main mold.


The piece is only about 0.055" thick . . . even with 3 layers of CSM. The fiberglass calculator indicated that 3 layers of 1.5 oz CSM would result in a 0.125" thick part, using hand lay-up. So, it looks like the vacuum infusion compresses the mat by about 55%.

I would expect stitched bi-axial (1708) cloth would compress a bit less than CSM.

Anyway, interesting day, messing around with VARTM. Each time I infuse a part/mold, I learn a few things . . .

 

[tpenfield]

Ladder Hatch Molds . . .

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I am all set with the ladder hatch molds. They will just need a coating of PVA before making the hatches.

Now on to the main platform mold . .

 

[oldrem]

Looks like you're making some great progress and learning a ton along the way.

 

[tpenfield]

Quick update regarding laminate thickness. . .

I checked the the thickness of the dry laminate for both the CSM and the 1708 to get an idea of the compression during the vacuum infusion.

I got . . .

CSM = 0.019”

1708 = 0.027”

Three layers of CSM, as I used on the test piece, would be (3x 0.019”) or 0.057” dry.

The test piece after curing measured 0.055” , almost the same as the dry thickness of the layers.

BTW - the glass/resin calculator for hand layup shows 3 layers of CSM being about 0.125” thick, so it shows you how much extra resin is used in hand layup.

Using the thickness information, I can predict the thickness of the final part, as I plan on using 1 layer of CSM, followed by 2 layers of 1708, then 1/2” of foam, and then 2 more layers of 1708.

So. . .

0.019
0.027
0.027
0.500
0.027
0.027
= 0.627”, call it 5/8”

I had been targeting 3/4” thickness for the platform, but 5/8” will do.


One concern I have is the thickness of the mold using just 3 layers of CSM. I am going to need to bulk up the laminate to some extent as well as add some stiffeners.

It is good that I ran the test piece, because it not only proved out the infusion process, it also provided better laminate thickness information. :thumb:

 

[tpenfield]

Just thinking ahead . . .

It certainly looks like I will need to add some bulk (thickness) to the mold. I could probably add some ribs to the platform mold using some wood strips, and also add some woven roving in various places.

I will probably run another series of tests to see how the infusion and wet-out process will work if I sandwich some wood strips between the layers of CSM.

I won't be back at it for another couple of weeks, and by then I should have the TBC inhibitor. So, I could also test the TBC inhibitor vs. the MCP catalyst to see which give better overall results of open time, cure time, and resulting hardness of the cured polyester.

FWIW - I ran another test of the MEKP vs. the MCP catalyst as a 'pot life' test. I had 3/4 oz of poly in 2 medicine cups. One activated with MEKP and the other activated with MCP, both @ 2%.

The starting temperature of the resin (per IR gun) was 55 F. (yes my garage is cold )

Rather than pouring the resin onto a sheet, as I did before, I left it in the cups, allowing them to build up more heat.

The MEKP/poly started to gel @ about 30 minutes.

The MCP/Poly started to gel @ about 70 minutes.

The MEKP/Poly reached a temp of about 140F as it cured

The MCP/Poly reached only about 70 F as it cured.

The MEKP Poly was rock hard after about 3 hours

The MCP/Poly took about 6-8 hours to harden, and was not as hard (it seems) as the MEKP/Poly.

Based on that test, I'd like to see if a MEKP/TBC/Poly combination exhibits any different physical character in the final cure.

Hopefully, with this additional 'testing' under my belt, I'll be ready to infuse the platform mold.

 

[Mad Props]

I know absolutely nothing, but I wonder if the styrene in the CSM took a long time to break down because of the small amount of resin and if that would have any affect on the saturation?? Probably way off, but just a thought.

Also, I could see the resin flowing much much better with woven or cloth vs. CSM since half of the fibers are consistantly oriented so they will allow it to flow through the weave and tow more effectively. CSM, it just a random orientation of fibers so theres no clear path for it to follow...

Once again, I know NUHSING!

 

[tpenfield]

Not sure about styrene in CSM . . . usually the styrene is in the resin. The resin that I'm using is about 35% styrene.

Yes, CSM does not flow as readily as a cloth fiber. Much of the resin flow is downward into the mat rather than laterally across it.

To your point though, the lack of flow characteristics of CSM may be why it took the resin about 25 minutes to flow out the last 1-2 inches of mat during the test.

 

[Mad Props]

Sorry.. meant binder, not styrene... CSM has a binder that holds all the fibers together that dissolves in styrene... that's why csm takes a few minutes to go transparent when wetting out with resin.

 

[tpenfield]

Quick update . . .

I received what would be a life-time supply of TBC inhibitor. (I bought the smallest quantity that I could get at retail)

I won't be back at it with the platform mold until next weekend (March 9-10th). I plan on running another set of tests, putting MEKP/TBC inhibited resin vs. MCP activated resin to see what would work out best.

I also got a perforation roller to add some perforation (tiny holes) to the peel ply. This should help the resin get through the peel ply layer faster and have more time to saturate the resin.

I'll also run a viscosity test of 'cold' resin (60 F) vs. warmer resin (70 F) to see how much of a difference 10F makes. Additionally, I may try a 5% thinning of the resin to see what difference that makes. . . . Lots of balls in the air.

Since the 3 layers of CSM amounted to not very much in the thickness department, I'm going to run another test piece with 3 layers of CSM and 1 layer of 24 oz WR. . . . similar to how the platform hatch molds are done. If I can get that laminate 'stack' to infuse using all of my latest 'tricks' then I'll probably go with it for the main platform mold.

I've already started laying out the resin runners and associated 'plumbing' for the resin flow for the swim platform.

 

[kcassells]

I've always read to understand thinning out the resin is a no no. Just saying.