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Ted
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I am currently doing a DIY project of making an extended swim platform for my boat. The platform is fairly large measuring 8 feet x 4 feet (2.4 m x 1.2 m). I am making a mold from a plug and then will make the actual 'part' from the mold. The platform design is of moderate complexity, having a step-down section to it and 'pylons' on the sides. The total area of fiberglass is about 40 sq. ft. (3.8 sq m) due to the complexities of shape. I plan on using VARTM in order to achieve good conformity of the fiberglass to the various shapes of the platform, and hopefully to apply the resin in one step vs. a more labor intensive process of hand layup. I'll be using polyester resin to make the mold and vinyl ester to make the part. One concern right now is finding ways to reduce the 'fill' time of the VARTM mold/bag considering that poly resin has a fairly short 'open' time as compared to VE or epoxy resin. In order to get a reasonable thickness of laminate, I plan on using 3 layers of 1.5 oz chopped stand mat. Then I will add stiffeners and reinforcements as hand layup after the vacuum bagging is complete. I figure that the faster I can get resin into the mold/bag and going through the flow media to all areas of the mold, then the more time the resin has to flow into and saturate the fiberglass. My plan is to have lots of resin runners throughout the mold so that the resin does not have to travel very far. One idea that I am considering is to pressurize the resin pot slightly, which is more typical of an RTM process, so that the resin is drawn through the tubing and into the runner system and flow media by both the vacuum from the bag and the pressure from the resin pot. I have done some searching and have not found much in terms of trials and experimentation of actually putting pressure into the resin pot, rather than merely relying on vacuum. My thinking is that with just vacuum to move the resin from the pot to the mold, you are limited to 1 atmosphere of pressure. With both vacuum and pressure in the pot, you can go beyond 1 atmosphere of pressure. (within reason of course). I am wondering if anyone has thoughts, comments, or experience in using both vacuum and pressure to get the resin to move to where it needs to go faster than it normally would with just vacuum? Thanks in advance for any comments/insight/adverse effects.
Regards, tpenfield
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Fasta
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+xI am currently doing a DIY project of making an extended swim platform for my boat. The platform is fairly large measuring 8 feet x 4 feet (2.4 m x 1.2 m). I am making a mold from a plug and then will make the actual 'part' from the mold. The platform design is of moderate complexity, having a step-down section to it and 'pylons' on the sides. The total area of fiberglass is about 40 sq. ft. (3.8 sq m) due to the complexities of shape. I plan on using VARTM in order to achieve good conformity of the fiberglass to the various shapes of the platform, and hopefully to apply the resin in one step vs. a more labor intensive process of hand layup. I'll be using polyester resin to make the mold and vinyl ester to make the part. One concern right now is finding ways to reduce the 'fill' time of the VARTM mold/bag considering that poly resin has a fairly short 'open' time as compared to VE or epoxy resin. In order to get a reasonable thickness of laminate, I plan on using 3 layers of 1.5 oz chopped stand mat. Then I will add stiffeners and reinforcements as hand layup after the vacuum bagging is complete. I figure that the faster I can get resin into the mold/bag and going through the flow media to all areas of the mold, then the more time the resin has to flow into and saturate the fiberglass. My plan is to have lots of resin runners throughout the mold so that the resin does not have to travel very far. One idea that I am considering is to pressurize the resin pot slightly, which is more typical of an RTM process, so that the resin is drawn through the tubing and into the runner system and flow media by both the vacuum from the bag and the pressure from the resin pot. I have done some searching and have not found much in terms of trials and experimentation of actually putting pressure into the resin pot, rather than merely relying on vacuum. My thinking is that with just vacuum to move the resin from the pot to the mold, you are limited to 1 atmosphere of pressure. With both vacuum and pressure in the pot, you can go beyond 1 atmosphere of pressure. (within reason of course). I am wondering if anyone has thoughts, comments, or experience in using both vacuum and pressure to get the resin to move to where it needs to go faster than it normally would with just vacuum? Thanks in advance for any comments/insight/adverse effects. Why such a rush for a one off part? I have a done a number of marine parts now with vinylester infusion resins and PVC foam core using resins with 75min pot life with reasonable success. Going too fast may force the resin to track through easy flow channels (if there are any) and leave areas of dry glass. Slower is safer in my opinion. The actual resin infusion is always the fastest part and all over within 2-3 hours for parts that take days and weeks to do the dry layups/ cores and bagging set ups. Worst case is that it can also gel on you and leave you short of infusing the complete job.
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Ted
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Group: Forum Members
Posts: 20,
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+x+xI am currently doing a DIY project of making an extended swim platform for my boat. The platform is fairly large measuring 8 feet x 4 feet (2.4 m x 1.2 m). I am making a mold from a plug and then will make the actual 'part' from the mold. The platform design is of moderate complexity, having a step-down section to it and 'pylons' on the sides. The total area of fiberglass is about 40 sq. ft. (3.8 sq m) due to the complexities of shape. I plan on using VARTM in order to achieve good conformity of the fiberglass to the various shapes of the platform, and hopefully to apply the resin in one step vs. a more labor intensive process of hand layup. I'll be using polyester resin to make the mold and vinyl ester to make the part. One concern right now is finding ways to reduce the 'fill' time of the VARTM mold/bag considering that poly resin has a fairly short 'open' time as compared to VE or epoxy resin. In order to get a reasonable thickness of laminate, I plan on using 3 layers of 1.5 oz chopped stand mat. Then I will add stiffeners and reinforcements as hand layup after the vacuum bagging is complete. I figure that the faster I can get resin into the mold/bag and going through the flow media to all areas of the mold, then the more time the resin has to flow into and saturate the fiberglass. My plan is to have lots of resin runners throughout the mold so that the resin does not have to travel very far. One idea that I am considering is to pressurize the resin pot slightly, which is more typical of an RTM process, so that the resin is drawn through the tubing and into the runner system and flow media by both the vacuum from the bag and the pressure from the resin pot. I have done some searching and have not found much in terms of trials and experimentation of actually putting pressure into the resin pot, rather than merely relying on vacuum. My thinking is that with just vacuum to move the resin from the pot to the mold, you are limited to 1 atmosphere of pressure. With both vacuum and pressure in the pot, you can go beyond 1 atmosphere of pressure. (within reason of course). I am wondering if anyone has thoughts, comments, or experience in using both vacuum and pressure to get the resin to move to where it needs to go faster than it normally would with just vacuum? Thanks in advance for any comments/insight/adverse effects. Why such a rush for a one off part? I have a done a number of marine parts now with vinylester infusion resins and PVC foam core using resins with 75min pot life with reasonable success. Going too fast may force the resin to track through easy flow channels (if there are any) and leave areas of dry glass. Slower is safer in my opinion. The actual resin infusion is always the fastest part and all over within 2-3 hours for parts that take days and weeks to do the dry layups/ cores and bagging set ups. Worst case is that it can also gel on you and leave you short of infusing the complete job. My main concern is making the mold with the poly resin. I think when I make the part with the VE resin, there will be more time before the resin starts to gel. Poly may be only about 15-20 minutes of infusion life - until it starts to gel and the flow through the fabric stops.
Regards, tpenfield
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oekmont
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You may use polyester inhibitor to raise the pot life to any time you want.
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Ted
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I like the idea of an inhibitor to slow the gel time. Thank you ! I have taken a quick look at the online fiberglass material suppliers and have not found inhibitors. Is there a particular brand/type that I can be looking for? It sounds like it may not be an everyday item for the DIY crowd. Any product names would be helpful. (thanks  ) Any additional ideas to speed things up and/or slow the resin down?
Regards, tpenfield
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oekmont
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Search directly for inhibitor instead of searching in shops you already know.
I got mine from phd24.de.
There are too many good products out there to stick to a few shops.
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Ted
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Group: Forum Members
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+xSearch directly for inhibitor instead of searching in shops you already know. I got mine from phd24.de. There are too many good products out there to stick to a few shops. I found some information online . . . It looks like there are various types of inhibitors, some to address the gel time and others used to address shelf life. Here is some data that I found on the Eastman website for their various inhibitor products. It looks like standard poly resin ( labeled 'control' ) starts to gel in as little as 5 minutes. and reaches peak exo at about 20 minutes. It looks like the 'HQ' or the 'THQ' types are preferable. Some of the product information talks about a oxygen reaction with the HQ type. I'm not sure if vacuum bagging would affect that in any way. I'm thinking the 'THQ' type would be better (???) . . . at 200-300 ppm it seems like it would extend gel time adequately for infusion fill and saturation. Being a novice at the details of resin chemistry, I'm just wondering if I am on the right track here? (I'm much more of a physics guy than chemistry ) 
Regards, tpenfield
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oekmont
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Group: Forum Members
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I don't know anything about these nomenclatures. But the thq figures seem to fit best with my experience. It's kind of an exponential function over the inhibitor concentration.
If it helps you, my inhibitor is based on a 10% 4-tert.-butylcatechol solution. In summer I tent to use a drop or two for certain resins (I'm looking at you, ec's high gloss primer).
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Ted
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Group: Forum Members
Posts: 20,
Visits: 337
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+xI don't know anything about these nomenclatures. But the thq figures seem to fit best with my experience. It's kind of an exponential function over the inhibitor concentration. If it helps you, my inhibitor is based on a 10% 4-tert.-butylcatechol solution. In summer I tent to use a drop or two for certain resins (I'm looking at you, ec's high gloss primer). OK, thank you. I have placed an inquiry with the fiberglass shop where I bought the resin. Hopefully they can recommend an appropriate inhibitor for the resin.
Regards, tpenfield
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oekmont
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Group: Forum Members
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I am quite certain, that the inhibitor works for all mekp caralysed systems. Because it inhibits the same functional groups, that are activated by the mekp. And i can say for my inhibitor, that it worked with every resin so far. About 10 different systems.
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