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Dravis
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I have a constant 21 - 22 degrees in my workshop -- I use 1,5% for both the EC Pattern coats --- otherwise I find that they "set" very abruptly.. I find that you need to develop a certain amount of skill to work with Polyesters or Vinylesters ... more so than Epoxy -- I also hate the smell of large amounts of Styrene .. 
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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Rich (Staff)
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Hi Turk,
Yes, 5g equates to 2% of 250g. There is a degree of adjustability though, if you find it cures too quickly or you simply need more working time, you can lower the catalyst ratio slightly. 21'C is about the normal ambient condition quoted on most datasheets but its certainly warmer than over here in the UK at the moment - the warmer the temperature you work in, the faster the primer (or resin/gelcoat/etc.) will cure so with anything polyester (or vinylester) based gives you the added benefit of being able to adjust the catalyst amount to account for the temperature.
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TURK
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Hi Richie, And many thanks for taking the time to respond 
Your math must be spot on as it's close to what I have found out.
Originally I was going about it totally the wrong way, I began looking at the online conversion tables and calculators on various suppliers websites ( should be one on here as well I think ). Unfortunately all of those are for wet laying glassfibre so that's taken into account.
The answer is really in the usage guide of the product, but for newbies it's not understood. What I did in the end was to half the information given. so ...... 1Kg of 'Pattern-Coat Primer' per 1m² which is 10,000 cm² 500g of resin - covers 5,000 cm² 250g of resin - covers 2,500 cm² 125g of resin - covers 1,250 cm² So on and so forth ....... may be not the conventional way to do it, but then I'm not a conventional sort of guy ! 
Also, Catalyst ...... 2% @ 250g = 5 grams ? My intentions are to build up the layers of resin, and sand back till I've got the required dimensions. My final coat will be 'Pattern-Coat High-Gloss'. My workshop is currently 21°C but can be warmed up if necessary. Many thanks for your help TURK
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Rich (Staff)
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Group: Administrators
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Hi Turk, 826cm2 equates to 0.0826m2 - so you'll be looking at around 80-90g (0.862 x 1kg) of pattern coat to cover at a thickness just shy of a mm. You'll be sanding and fairing back through this so your final thickness per layer is likely to be a lot less than this. Generally though, it will use as much as it requires, the first coat especially may draw into the MDF if it is unsealed and it is likely that you'll need to apply a few applications to achieve a flawless finish and there may still need to be some filling with body-filler between stages to ensure that you have a smooth transition between sections of MDF. 
Remember that, as with all resins, temperature can have a big effect on the cure speed so if it is particularly warm where you're working, you may want to use a slightly lower catalyst ratio to slow down the reaction and to give you more working time.
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TURK
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Hi all, OK, I've worked out all the dimensions of all six sides. W=14cm x L=15cm x H=7cm all x2 are there opposing sides. Give me = 826 square centimetres Now that I know how much surface I have to cover ......... how do I work out how many grams of resin I need ? Sorry about all the questions, you pros would of been newbies years ago, how did you solve the problem ?
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Dravis
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Group: Forum Members
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1 square cm = 0,0001 square meter .. 
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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TURK
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Group: Forum Members
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Dravis (24/09/2015)
No -No no -- You do NOT need the VOLUME -- You need the SURFACE area ..
Cut out some soft cloth or tissue cover the "plug" and cut the tissue so it just covers the surface of the "headlamp bracket" then measure the AREA in Square meters of the sheet.
This method is plenty accurate enough .. Hi Dravis, I really appreciate the help. I just realised my mistake  I was just reading one of those BBC Bit Size math tutorials for dummies, and relised I was measuring the interior of the 'box contents ! ( volume )
Your analogy of the cloth covering is spot on. Only my cloth would be centimetres in size. The only guidance on the Pattern_Coat Prime expresses it's coverage in 1kg=1 sqr metre.
Those plugs will have radius'ed corners when I get my combination sanding machine later today. |
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Dravis
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Group: Forum Members
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Just some comments on your Bracket "Plugs" I assume that, since you are going to "pattern" coat them, you are making the "pattern" or "plug" to make the Mold from?
To my eye, you have a lot of very sharp corners on those plugs ... I would put a bit more of a "radius" on all those sharp corners .. I personally only use smaller radius than 5 mm on very small parts, using very light weight CF weaves.
You may be able to make a usable mold from such a sharp edged "pattern" but it will be VERY difficult to avoid the final Carbon-fibre bridging in the corners and you may get corners that are only resin, with no fibres in there.. This will make the corners brittle, and compromise the strength of the bracket.
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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Dravis
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Group: Forum Members
Posts: 592,
Visits: 1.9K
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No -No no -- You do NOT need the VOLUME -- You need the SURFACE area ..
Cut out some soft cloth or tissue cover the "plug" and cut the tissue so it just covers the surface of the "headlamp bracket" then measure the AREA in Square meters of the sheet.
This method is plenty accurate enough ..
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Many thanks Dravis, My MDF plugs are ready, all flatted, sanded, just ready for the Pattern-Coat Primer. They're basically box shaped. (L)150mm x (W)140mm x (H)70mm
So I have to workout the volume of said part.V=L x W x H ( V=15x14x7 ) to get the volume area in cm3the total is 1470 cubic centimetres
I then converted that volume into weight and got 52 fl.oz ( imperial )
That's an awful lot of resin just for a small plug, that's over 2 pints per plug !
This is what I'm covering with one layer of resin >>
There's two in the picture, but in all I have four as they're modular construction. But I'll be doing them individually.I'll apply more coats of resin if required. |
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