andyscotland Posted November 7, 2019 Author Share Posted November 7, 2019 1 minute ago, SteamyTea said: Never used it, or seen it in action. But I have used PU resins a lot in the past. They are tolerant of moisture, some actually need it to cure. I seem to remember that they are more viscous, so may seem a bit alien to people that are used to polyester, and I am not sure how easily they break down the binder in the mat. There are different types of binder for mat and woven cloth does not have any at all, so that may be an option. Call them up and ask for a sample. You are on the wrong side of the country too. Thanks - could do but already have all the GRP materials on-site and not sure I'll be able to return/shift them so would be a fair bit of waste to switch now (plus would potentially need to go back over the section that's already done?) I did look at a couple of PU resins at the time - didn't see that one you linked but it says it's rain resistant "within two hours" so maybe not much better than what I have. http://www.ultra-flex.com/ looked more promising, moisture curing and instantly rain resistant but when I was researching it didn't appear to have a fire rating, which I need. 9 minutes ago, Onoff said: Tell me more, like paint is it? All the ones I looked at were basically the same setup as GRP (resin, glass mat, resin) though some needed priming/had two coats of the same thing instead of separate base and topcoat/had thinner matting. But same general ballpark of an idea. Link to comment Share on other sites More sharing options...
SteamyTea Posted November 7, 2019 Share Posted November 7, 2019 39 minutes ago, andyscotland said: could do but already have all the GRP materials on-site May only be a case of changing the resin. You may find another use for the polyester, make a boat, or a pond, some guttering. Or sell it to the Boy Scouts to make canoes. Just thinking that the rain is going to be on and off for the next, I don't know, 40 years. 1 1 Link to comment Share on other sites More sharing options...
andyscotland Posted November 7, 2019 Author Share Posted November 7, 2019 (edited) @SteamyTea might make a boat and sail over the ocean and far away to the land where GRP cures ? ? Good thought tho, will consider it... Edited November 7, 2019 by andyscotland Link to comment Share on other sites More sharing options...
SteamyTea Posted November 7, 2019 Share Posted November 7, 2019 13 hours ago, andyscotland said: sail over the ocean and far away to the land where GRP cures A guy I knew at university worked in Barbados for several years as a boat builder/repairer. I think he sailed back to Falmouth in a boat he build. I often wonder why he came back. 1 Link to comment Share on other sites More sharing options...
andyscotland Posted November 17, 2019 Author Share Posted November 17, 2019 Well, it is up and the top on. The scaff structure feels very sturdy (I ordered a bunch of spare lengths and we added diagonal braces as we went till it all felt rigid). Only took two lengths of scaff across the top (with braces to centre span) before the sides felt rock solid. So decided to leave most of the rest off and support the tarp with rope along the lines of @Cpd suggestion. That's holding well, will add more to make it more of a web but ran out of time today. As per @Visti the cover is just sitting over it, tied off to the building rather than the scaff. Went with a big 8m x 10m sheet of clear mono cover tarp which appears to be much the same as the scaffold sheeting @Ed Davies recommended. Foolishly ordered the long sides to have the fewest pieces, had an entertaining time trying to juggle a couple of 21' horizontals and freestanding legs before they were clamped together. With hindsight should have done that as 8' lengths with couplers and built it a bay at a time... The wedge-joined-to-a-rectangle shape made it impossible to get the tarp totally taut as a single plane. So instead decided to tension it into natural sags that run downwards to the outside edges at front and back (like a poor man's butterfly roof) - had a bit of light rain today and it's run into the fold and out as expected. Still plenty of headroom under the droops to work. So far very little wind and the forecast for the next fortnight is fairly calm and light rain so hopefully it will hold up ok. Now just need to get the old tarps off the roof itself, will use them to enclose the sides against driving rain / splash from the tarp "gutters". As it's going to be pretty draughty up there my plan now is to borrow a couple of electric patio heaters to warm/dry the boards rather than trying to heat the surrounding air. 3 Link to comment Share on other sites More sharing options...
SteamyTea Posted November 18, 2019 Share Posted November 18, 2019 8 hours ago, andyscotland said: So instead decided to tension it into natural sags that run downwards to the outside edges at front and back On 07/11/2019 at 09:12, andyscotland said: might make a boat and sail over the ocean and far away to the land where GRP cures So you have now made the sail, get the hang of the GRP and you are well on your way to making a boat. Make sure it is warm enough to lay up the GRP. You could use cobalt accelerator if it looks like the temperature is too low. If very low, then amine accelerator (have used that for very quick repairs when about 0°C. 1 Link to comment Share on other sites More sharing options...
ProDave Posted November 18, 2019 Share Posted November 18, 2019 It was -7 here last night and forecast to be even colder tomorrow. I have pretty much given up hope of getting my last velux window in now before the spring. 1 Link to comment Share on other sites More sharing options...
andyscotland Posted November 18, 2019 Author Share Posted November 18, 2019 4 hours ago, SteamyTea said: So you have now made the sail, get the hang of the GRP and you are well on your way to making a boat. Make sure it is warm enough to lay up the GRP. You could use cobalt accelerator if it looks like the temperature is too low. If very low, then amine accelerator (have used that for very quick repairs when about 0°C. Cromar reckon out of the tin it's OK down to 5°C. Cold for that today (nowhere near @ProDave's -7 thankfully, though low of -4 tonight) but looks like it will warm up again later in the week. If it's just under (say 3-4°C) towards the start/end of the day, I'm thinking that would be OK so long as the resin has been in the warm and I've a heat lamp gently warming the boards before I start / while it cures? Or is it crucial that the air temperature is also over the minimum? Link to comment Share on other sites More sharing options...
Onoff Posted November 18, 2019 Share Posted November 18, 2019 Isn't RH an issue with doing GRP? Link to comment Share on other sites More sharing options...
SteamyTea Posted November 18, 2019 Share Posted November 18, 2019 (edited) It is a bit if a combination of things. RH is really only a problem when very high, and in a hot place. If you warm the boards, curing can start sooner on the first layer. But don't think that will be a problem. What may be worth while is upping the catalyst a bit if the final layer is put down more that about 15 to 20 minutes after the first layers. Trouble with having the resin warm and the boards cold is that it reduces the pit life of the resin. Do a metre by metre square at a time until you get a feel for what is going on. And don't do too much if there is a chance that it is not going to cure in about an hour and a half. Curing will not catch up the next day. Sun us out in Aylesbury. Edited November 18, 2019 by SteamyTea 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted November 18, 2019 Share Posted November 18, 2019 (edited) Also, as a rule of thumb when using CSM, weight it, then weight out twice the amount of resin. You won't be far out. Edited November 18, 2019 by SteamyTea 1 Link to comment Share on other sites More sharing options...
andyscotland Posted November 30, 2019 Author Share Posted November 30, 2019 Wee update : tent is still up and weatherproof, have had 3 electric patio heaters on low continuously and a dehumidifier up there. It's not totally sealed at the corners/edges but I've closed up the worst of the drafts. The temperature is consistently a good few degrees above outside air, the dehumidifier has cleared up the condensation/dew that was initially forming on the inside and then dripping back onto the boards. Now getting solid 5-6% readings from my electronic moisture meter. Did a couple of small sections of the GRP in lunch breaks last week, sanding and acetoning at the joins between each day's work and it's going down fine. Also much more efficient being able to leave all the tools and materials up there overnight rather than having to bring everything down and back up. It dropped to 2° in there overnight while it was -5 outside, but otherwise has always been 5° or higher. Good demo of the power of solar gain too : yesterday lunchtime it was 2° outside but so sunny that with the heaters off the boards and air were at 22°! Bit of luck I'll finish the laminate this weekend, then going to sand and acetone the whole thing, put a thin coat of resin and then topcoat as I've read that can get a better bond if there's been a delay in getting the topcoat down. So far seems like the bonkers plan is working! 3 Link to comment Share on other sites More sharing options...
SteamyTea Posted November 30, 2019 Share Posted November 30, 2019 3 hours ago, andyscotland said: a thin coat of resin and then topcoat as I've read that can get a better bond if there's been a delay in getting the topcoat down. I am taking a guess that it is not an environmental resin, these tend to have a wax additive in them. It feels slippery when cured, so you would know. Bit of sanding sorts it out anyway. Link to comment Share on other sites More sharing options...
Cpd Posted November 30, 2019 Share Posted November 30, 2019 8 hours ago, andyscotland said: So far seems like the bonkers plan is working! Always great when a bonkers plan actually works ! Best of luck. 1 Link to comment Share on other sites More sharing options...
andyscotland Posted December 1, 2019 Author Share Posted December 1, 2019 9 hours ago, SteamyTea said: I am taking a guess that it is not an environmental resin, these tend to have a wax additive in them. It feels slippery when cured, so you would know. Bit of sanding sorts it out anyway. I'm not sure what an environmental resin is but it doesn't feel slippery. It's Cromar ProGRP - they say it's "pure resin, not blended". Link to comment Share on other sites More sharing options...
SteamyTea Posted December 1, 2019 Share Posted December 1, 2019 (edited) 5 hours ago, andyscotland said: Cromar ProGRP What colour is it before you add any hardener? Edited December 1, 2019 by SteamyTea Link to comment Share on other sites More sharing options...
andyscotland Posted December 1, 2019 Author Share Posted December 1, 2019 1 hour ago, SteamyTea said: What colour is it before you add any hardener? Blue (slightly greenish) then turns brown-green once catalysed. Link to comment Share on other sites More sharing options...
SteamyTea Posted December 1, 2019 Share Posted December 1, 2019 Sounds like a Norpol resin, as they say, it has nothing added. It can be a bit harsh on the fingers. Link to comment Share on other sites More sharing options...
andyscotland Posted December 1, 2019 Author Share Posted December 1, 2019 (edited) 10 minutes ago, SteamyTea said: Sounds like a Norpol resin, as they say, it has nothing added. It can be a bit harsh on the fingers. I've been fully gloved up : went through a billion latex gloves in the early stages, then switched to some trusty marigolds which are lasting much better! I have managed to laminate my trousers to my knees a couple of times but not noticed any ill effects once unstuck ? Edited December 1, 2019 by andyscotland Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now