Welcome guest, is this your first visit? Create Account now to join.
  • Login:

Welcome to the NZ Hunting and Shooting Forums.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed.

Night Vision NZ Alpine


User Tag List

+ Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 15 of 19
Like Tree5Likes

Thread: Carbon fibre/epoxy gurus help please

  1. #1
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606

    Carbon fibre/epoxy gurus help please

    Hey team.

    Last year I made my own carbon fibre stock. Was a really rewarding process and I learned a hell of a lot. The rifle has been used multiple times since I made it without issue. On my last outing a couple of months ago I was met with some very adverse weather in the form of torrential horizontal rain. I would have been out in it for about 4 hours. All my other hunts with the rifle have been in good weather.

    I noticed at the time that there were bluish white marks forming in places on the stock that did not rub off. I can only assume that moisture managed to get into it?? After the hunt I made sure to dry the rifle really well. I took the rifle out today just to have a look and have found many marks and blemishes all over it, these are in the places where the white mares were.

    Can anyone tell me what has happened? I am about to embark on a second stock build, and if I have made a mistake somewhere I would like to rectify it before I begin.

    The stock is built on a powlonia blank. I laid one layer of epoxy down. When it was tacky I laid the carbon, followed by three layers of epoxy, sanding each then finishing the final coat with very fine paper. I waited until the epoxy was hard before sanding and then adding the next layer. And yea I am aware I was a touch vigorous with my initial sanding and went through the carbon in places.

    My current plan is to sand the marks out, then put a coat or two on at the same time as my new stock.

    I am not sure if it user error that has caused the blemishes or not?

    Appreciate your thoughts.

    Name:  IMG_2200.jpeg
Views: 552
Size:  2.78 MBName:  IMG_2201.jpeg
Views: 526
Size:  2.80 MBName:  IMG_2202.jpeg
Views: 540
Size:  2.94 MBName:  IMG_2203.jpeg
Views: 511
Size:  3.40 MB

  2. #2
    Member
    Join Date
    Oct 2020
    Location
    Gisborne
    Posts
    801
    Hi Delphus, I’ve not seen that before. Hunt in all weather with mine for over 3 years now. Only thing I can take a stab at could be the resin not mixed fully, or the ratios not quite right. Fully cured resin is impermeable and super hard wearing. Is it tackey or gooey at all?

  3. #3
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Yeah I thought it was weird as well. I’m thought I mixed properly and got proportions correct, but I could have gotten it wrong. Not soft at all, still hard. Odd

  4. #4
    Member
    Join Date
    Oct 2020
    Location
    Gisborne
    Posts
    801
    Yeah, just rough sand and patch over it and re finish. I do all mine in layers now. Gives a free layers in stress areas and tight curves and is easier to get a better finish. I gladwrap and tape after each application
    Delphus likes this.

  5. #5
    Member chainsaw's Avatar
    Join Date
    Jul 2014
    Location
    Norf
    Posts
    5,771
    Watching with interest to see if any epoxy gurus can shed light on possible causes. Have done 2 Paulownia CF epoxy stocks myself. Have not encountered this issue but have not had stocks out in torrential rain either. I imagine a good sand & couple of epoxy coats would remedy it. What brand of epoxy were you using ?

  6. #6
    Member HILLBILLYHUNTERS's Avatar
    Join Date
    Sep 2013
    Location
    Southland
    Posts
    322
    hasn't been by a camp fire has it ?

  7. #7
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Quote Originally Posted by HILLBILLYHUNTERS View Post
    hasn't been by a camp fire has it ?
    Nope not near any open flame. After I got back from the trip I angles the heat pump to blow right o Tobit for a few hours. Was warm when I put it away, but still looked fine.

  8. #8
    Member
    Join Date
    May 2022
    Location
    tauranga
    Posts
    505
    Has it been exposed to elevated temp like in the ca in summer or even outside under the sun? standard epoxy have a transition glass temperature arround 60-70deg which is the temp at which the epoxy get soft. I had hydrofoil wrapping and surface defect appearing while stored in the car in summer. Check the datasheet of the epoxy you used and look what’s the TG (transition glass temp). If you do a tapping test with a 6mm bolt (just tape it slightly, don’t hammer it) on the laminate does it sound different than on the carbon that is undamaged?
    Delphus likes this.

  9. #9
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Quote Originally Posted by Scott Cowan View Post
    Yeah, just rough sand and patch over it and re finish. I do all mine in layers now. Gives a free layers in stress areas and tight curves and is easier to get a better finish. I gladwrap and tape after each application
    Gladwrap and tape after each epoxy layer? At what point in the drying do you wrap it?
    I’ll sand and patch this one when I do the new one. It’s still a ways away as I have only just inletted it. Bedding next then I the shaping and sanding of the stock

  10. #10
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Quote Originally Posted by tibo View Post
    Has it been exposed to elevated temp like in the ca in summer or even outside under the sun? standard epoxy have a transition glass temperature arround 60-70deg which is the temp at which the epoxy get soft. I had hydrofoil wrapping and surface defect appearing while stored in the car in summer. Check the datasheet of the epoxy you used and look what’s the TG (transition glass temp). If you do a tapping test with a 6mm bolt (just tape it slightly, don’t hammer it) on the laminate does it sound different than on the carbon that is undamaged?
    Hmm I’ll have a try tomorrow and see how it sounds. The o lay time this has been in the sun is when I have carried it. It’s my wallaby gun and I don’t spend much time sitting and glassing, just walking and shooting

    It has only been in the safe or transported to a block in the car. Never left in there. It does look like it has heated up though

  11. #11
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Quote Originally Posted by chainsaw View Post
    Watching with interest to see if any epoxy gurus can shed light on possible causes. Have done 2 Paulownia CF epoxy stocks myself. Have not encountered this issue but have not had stocks out in torrential rain either. I imagine a good sand & couple of epoxy coats would remedy it. What brand of epoxy were you using ?
    I used this kit. I spoke to the guy and he said I should use the UV stabilised epoxy co soldering it would be used in the great outdoors

    https://nzfg.co.nz/product/carbon-fibre-kit-2/

  12. #12
    Member
    Join Date
    Jul 2012
    Location
    Invervegas
    Posts
    5,210
    It could be "blush" - some epoxies are prone to this . . . Basically not cleaning enought between coats
    Delphus likes this.

  13. #13
    Member
    Join Date
    May 2022
    Location
    tauranga
    Posts
    505
    Quote Originally Posted by Tentman View Post
    It could be "blush" - some epoxies are prone to this . . . Basically not cleaning enought between coats
    Amine blush would happen straight away no? This kit you used is all good, I used it heaps. UV stabilise will help with the yellowing but it will still go bad if it goes past TG. Carbon heat really fast in summer, on a long walk with the rifle on your back it could happen. West system 105 Tg is 60deg for example Nz fiberglass kit would be similar.

    About UV, it could get to this point after long exposure but you would see it goes yellowish first
    Delphus likes this.

  14. #14
    Gkp
    Gkp is offline
    Member
    Join Date
    May 2018
    Location
    Queenstown
    Posts
    1,831
    release agent?

  15. #15
    Member Delphus's Avatar
    Join Date
    Feb 2019
    Location
    South Canterbury
    Posts
    1,606
    Quote Originally Posted by Gkp View Post
    release agent?
    Na shouldn’t be. I didn’t start the epoxy until well after the rifle had been bedded. I have it a good clean first too

 

 

Similar Threads

  1. Rem 700 SA Carbon Fibre stock
    By Redaxler in forum Firearms, Optics and Accessories
    Replies: 5
    Last Post: 16-01-2020, 03:42 PM
  2. Carbon Fibre Bipods
    By Bos in forum Firearms, Optics and Accessories
    Replies: 9
    Last Post: 09-05-2019, 10:17 PM
  3. Carbon Fibre Barrels
    By Kudu in forum Firearms, Optics and Accessories
    Replies: 9
    Last Post: 16-12-2018, 07:50 AM
  4. Carbon Fibre Stock
    By muzr257 in forum Firearms, Optics and Accessories
    Replies: 15
    Last Post: 14-05-2018, 04:38 PM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Welcome to NZ Hunting and Shooting Forums! We see you're new here, or arn't logged in. Create an account, and Login for full access including our FREE BUY and SELL section Register NOW!!