What NOBODY will tell you about MIXING GELCOAT!! WTF? 🤯
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- เผยแพร่เมื่อ 31 พ.ค. 2024
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Enjoyed the discussion about gelcoat however your measurements need clarification. By definition, 1 fluid ounce (volume) of water weighs 1 oz (weight) and this is because water has a density of 1. Gelcoat on the other hand is more dense than water. Depending on the supplier/brand its density could be anywhere from 1.1 to 1.4. This means that 1 fluid ounce of gelcoat will weigh 1.1 to 1.4 oz. This is why your 20 fluid ounces of gelcoat weigh 28 ounces on you scale. The graduations on the measuring cup and the values shown by your scale are volumes and weights respectively and will only match when the density of the fluid being measured is 1...i.e. water. If you took your measuring cups and measured a certain amount water, you will find that the scale will show that same value in weight simply because the density of water is 1.
Exactly!!! You nailed it! We are instructed to mix the materials "by weight". Weather it be Gelcoat, Resin, Bonding Putty, Fairing Compound, all should be catalyzed according to their weight. None of which are equal to water. Thanks for watching and commenting!
I read this again, and I agree with you. I have asked many "boat builders" and "fiberglass guys" "How much catalyst do you add a quart of Gelcoat?" The typical response is, "10 cc's to a quart". This would be undercatylized. The 32 oz quart of Gelcoat would weigh close to 40 oz or more and require 20 cc's for 1.5% MEKP. This is the point of the video.
If im mot mistaken, the cup measures oz volume, and the scale measures oz weight, two different measurements
Thanks for the video. And you added the blurp! Good video
Haha!! 🤣
Glad you enjoyed it!! More how-to's after the Bertram Project..
Great Video! Keep them coming 👍🏼
How many layers do you apply and how much time in between each or just one heavy coat?
Great question @mikeortiz5178 !! There is not a one-size-fits-all answer. It depends on what you are doing or trying to accomplish. Typically, I apply gelcoat in multiple coats. In mold application is more limiting than post finish application. In mold, I apply an almost "full-hide" coat then allow a gassing off period (a minute or two) to prevent porosity on the surface. I follow with a heavy coat to build film thickness hoping to achieve 30-40 mils wet. Sometimes more if I know I will need to sand the part. Post finish is a whole different animal. I usually apply 15 mils per coat. Sometimes more if filling porosity. Typically 3-5 coats because I will almost certainly sand the surface and either buff and polish or topcoat with paint. I will do a video for each application if there is enough interest. Let me know what you all want to see! Thanks for watching!
Duratec recommend fast acrylic thinner , any thoughts ? I don't have access to duratec products , i m facing problem with praying gelcoat even from a 3 mm nozzle with gel coat gun .
In mold or post finish application?
I have never tried fast acrylic thinner in gelcoat. My understanding is that Duratec is not a gelcoat. It is an addittive. Some type of acrylic enamel blend that is activated with MEKP.
I would start with styrene, upto 4-5% and increase the size of the nozzle orifice for in mold application. Use a dump gun or something similar like a spray bed liner gun.
Just to clarify, you calculotor is taking the resin or gelcoat weight, and converting that to volume ie; cc of mekp?
Good question!! I will have to go back a few years and dig up some notes. From memory, the ratio is calculated in weight and the conversion is the catalyst from weight to volume. But the magic really is that you can can use it quickly in the middle of a layup while wearing gloves and it works!! I get excellent results and amazing consistency!! Try it!!
Another huge benefit is that you can mix in any clean container. I use the marked cups to get close, when pouring off a pail, then catalyze according to the weight. You can also reuse any cleaned household containers. Simply zero the scale with the container on it, then add material, use the calculator and mix well!! Thanks for the question!!
Thank you, a new subscriber here
Awesome!! Thank for joining!!
I'm getting ready to do my first boat gelcoat repair and watching every video. You make a good point both about the stirring the gelcoat and weighing because the containers are not calibrated. One could take a container, fill it up with water to the intended line and weigh the water. If for instance you fill the container to 30 ml, the water should weigh 30 grams. Do this at several points to see if the container's marks are consistent. I would imagine that a batch of containers would be consistent. But when you change to a different batch or brand, you'll need to check it again. Did you check the calibration on the MEKP measuring device? The density of the gelcoat is about 1.1 so 20 ml will weigh about 22 grams. The density of MEKP is reported to be 1.17. Now my comment on your calculator: Is the input supposed to be fluid oz (volume) or weight oz(mass)? You inputted weight ounces and you didn't correct it for its density. The result of MEKP is a fluid measurement. The volume of 28.5 weight oz would be about 26 fluid oz. So for 1.75% by weight would require 0.5 weight oz of MEKP which is 0.426 fl oz which is 12.8 ml. 1.75% by volume is .0175 * 26 is .455 fl oz which is 13.65 ml. So the difference is 0.85 ml. Does that make a significance difference?
🤯
Wow.. detailed question.. I will get back to you with an answer when I can review your numbers. In the meantime, I suggest mixing a small batch with an exact ratio that you can scale up and tweak until you get 35- 40 minute gel-time.
Another Tip: KEEP YOUR GELCOAT IN THE CUP! A lot of people say to spread it out to give yourself more time. That is true with Epoxy. Polyester and Vinylester contain STYRENE. Styrene evaporates like a reducer and allows the materials to cure. Often gelcoat will cure MUCH slower if there is no wind evaporate the STYRENE. I will do a video showing how this works. It does the same in a cup.
@@vernesecustoms I just did two small gelcoats. I measured the drops of MEKP.
17 drops weighed 0.37 grams. then 27 drops weighed 0.82 grams. Using density = 1.17 gm/cc. 17 drops = .32 CC and27 drops = 0.7 CC. But there is a wide variation of gms per drop. Weighing is by far more accurate than counting drops.
@@ralphparker I agree!! I very rarely work on parts when guessing or "that ought to work" is acceptable!!
I'm not hating, but are the cups inaccurate or is the scale? I suspect a little of both?
And can you add a Metric option to the calculator?
It is a valid question. The mixing cups I have used are marked in volumetric ounces. Resin and especially gelcoat are heavier than most liquids. When measuring by weight (highly recommended), you will find the marks are off quite a bit, and you may be undercatylizing your materials. I am always trying to achieve the highest quality possible. This requires the material to be properly catylized.
I absolutely intend to add more features to the Calculator. The metric option will be one of the first! Thanks for watching and asking good questions!! 👍
I love watching these videos to learn for that "maybe, one day" but, don't tell my wife, I *may* be acquiring a boat when the weather gets warmer (I'm in Australia and winter hath come, with a vengeance). I'm also glad you showed spraying it on, however, a little more detail on that process might be good for me. Funny story, but I found a working air compressor in a park, so I'm keen to get my money's worth out of that.
I also wanted to say what a sensational job you did with the video, explaining everything you did excellently.
did you add resin in the gelcoat?
No Resin added. I try to keep Gelcoat in its purest form. I added Styrene in the video because Gelcoat that slightly aged will lose some Styrene even if the pail is sealed. A "tell-tale sign" of aged gelcoat is a sealed pail with side sucking in. Has someone advised adding resin to gelcoat??
Would of been nice to see your finished work...
Yes! More of these "how-to's" after the Bertram is finished. Check out: th-cam.com/play/PLDmp0sebeIM4wxDeHeuyh3nvWN8hCCyDg.html for more detailed videos
and by the way....I like the music.
Haha! 🤣 As do I!!
Why did you add more styrene to gelcote?
The Styrene evaporates as the material ages even if the pail is still sealed. It permeates the plastic bucket. The splash of styrene thins the gelcoat a fair amount and sprays much better. Thanks for asking!!
@@vernesecustoms
Thank you so much for your quick response.
Is it necessary to add styrene for casting f.g molds or just for boats finishing?
@alialhirsh7551 not necessary.
Can you tell me what spray gun you are using?
Sure! I use a DeVilbiss FLG 3 that I have had for about 12 years. I use the 1.8 mm tip 99% of the time. But this will only spray reduced gelcoat. To spray uncut gelcoat I use a cup gun or a dump gun some people call it. Thanks for watching and asking questions!!
@@vernesecustoms which way produces a smoother finish? I’m fine with reducing. I sprayed a area with uncut gel coat through a husky gun and it was very textured when I finished. Needless to say I have no desire to sand that much ever again lol.
@stevenmullin2661 I prefer to spray multiple coats with an additive called "Patch Aid". It thins the gelcoat and boosts the cure.
@@vernesecustoms Do you put patch aid in all the coats or only the final coat? And, how long do you wait between coats?
@matthewgalvin940 Good question! I have done both. Multiple coats with a pactch aid or wax additive and as a final coat and never noticed a difference. The deciding factor for me would be "How large is the part?". If very large, I will spray all coats with a surfacing additive. I like to see the previous coat firm up or start to gel if possible. The key is to allow a "gass off period"in between coats. I have zero porosity in the gelcoat this way. Thanks for watching!! 👍
Can you use acetone as a thinner instead of styrene?
NO. Never. For clean up ONLY. Anyone who says otherwise is unqualified to educate, in my opinion. This is a great question. I can only think of one particular occasion when I used Acetone to thin resin to waterproof plywood before rain got to it. Although it did work, the resin may have been rubbery as a result. Thanks for asking great questions!! 👍
@@vernesecustoms hmmm. Performance boat companies have been painting elaborate graphics with fades and pin lines for decades. All with gel coat and only using acetone as a thinner. The company I worked for is over 50 years old. Even the oldest boats look like new with a little polish, if needed.
@doncunningham3124 that is interesting. I am curious about the details of the application. In mold? Post finish? Every materials supplier I have asked says it degrades the gelcoat. I can NOT recommend it. Can you share the name of the company?
@@vernesecustoms I'm a rep now but unlike my peers, I come from the front lines. Not a classroom. During my decades of composite fabrication, I was told to use styrene by some and acetone from others. Both sides contradicted each other with conviction. That said, when I started working with high end performance boat companies, where beautiful gel coat graphics play a major role, acetone was used as a thinning agent. Never styrene. This includes painting mould surfaces as well as finished parts, after capping for example.
Sorry, I cannot give any specific company names because I currently work for the suppliers of these companies. I hope you can understand.
@doncunningham3124 still, I am very interested.. in specific ratios and application techniques used... can you share a simple recipe? For example: mixing 1 quart of polyester gelcoat @ 1.75% MEKP. What percentage of acetone did these companies use? What equipment was used for spraying? Light coats allowing acetone to flash? How did they avoid "alligatoring"? Was the finish protected with a clear coat? More questions brewing.. this sounds like a very specialized application and not for general purposes.
When you mention "ounces" it isn't clear whether you mean fluid ounces (measuring volume) or ounces of weight (avoirdupois ounce = 1/16 lb).
Hey Dave! Not sure which part of the video you are unclear about. Help me with a time stamp. When I refer to measuring by weight (on the scale), we are speaking about ounces in weight. When I measure the marks on the mixing cup, we are measuring in fluid ounces. I have been taught that resins and putties should be catylized and measured by weight.
@@vernesecustoms I mean even the online calculator doesn't specify "fluid ounces(1 oz = 1/32 Qt)" or "ounces (1 oz=1/16 lb)."
@davejoseph5615 the free MEK calculator is volumetric. It works great! The upgraded version is by weight. It is more precise.
can you roll this on for top coat
The short answer is No. However, I could make a 45-minute video on all the reasons why I advise against it. Certainly some people might disagree. First, this recipe is for spraying gelcoat. The gelcoat is applied in thin coats and allows the solvents to flash or evaporate. Nearly impossible to do with a roller. Next, the cured surface will remain tacky and require further attention. Either wetsanding and polish or a chemical scrub. Both would be challenging with a rolled finish. Thank you for watching! I hope this is helpful!
I can continue. A rolled gelcoat finished is typically thicker than the recommended film thickness or, at minimum, inconsistent. There will be porosity in the cured finish. Porosity hold dirt and moisture, resulting in a poor quality finish. There may be some tricks or additives that I am unaware of. If anyone knows of such, please comment below!
Thank you for clearing that up. What spray tip size did you say works best was it 1/8 or something. What state and city are you located in@@vernesecustoms
@Mr.Stubz. I use a 1.8 mm tip in this video. That is pretty much my "go to" for primers and spraying gelcoat for repairs or "post finishing" or out of the mold finishing.
4:40
Hahaa! The end??
Ever thought of adding a feature to make very small "preval" patch mixes? With MEKP having an option for drop wise? That would be super handy, what you have here is great don't get me wrong but it would up your game much more.. thanks for this great tool!!
Great suggestion! I just started working a solution for measuring in "drops". Testing it soon. I use the MEKP calculator religiously. I love the consistent result! Glad you are enjoying it too!! www.vernese.com/mek
A few questions: What browser do you use? Do you weigh or measure the gelcoat going into the PreVal? Do you reduce your gelcoat? If Yes, with what?
Tip: some browsers allow the "install app" feature. This puts a shortcut on your homepage. Very handy! 👍
Please cut the music
Will do! Thanks for the feedback!
I don't mind it honestly but the copyright bot will absolutely nail you for using it. Your mixing is fine but in general avoid music with lyrics for narrated videos.
@@smallpants Thanks! I certainly will not make a penny from this. But it is a great song!🤣
Agreed.
@@vernesecustoms I don't like the music in the background either. In your case is was borderline on being louder than your voice.
Styrene sucks, it’s a killer. Duratec additive, use a real gun like a Binks with a 68 tip and a pot.
Thanks for watching! Duratec has a place. It certainly dilutes gelcoat, and I typically use it as a final coat only on large parts. Most people undercatylize gelcoat and especially with Duratec addittive. 2% Folks!! All gelcoat and resin loose styrene as they age. The splash of styrene is mostly to replace what has evaporated. I have several Binks guns and pressure pots. Not my go to. Thanks for the input. Someone may get value from it!! More detailed videos later this year!!