Results 1 to 15 of 15
  1. #1
    Join Date
    Mar 2008
    Location
    Townsville, Nth Qld
    Posts
    4,236

    Default Veneering problem

    After gluing two sheets of veneer on a MDF substrate with epoxy, I would like to tape them together before putting them in a mechanical press, or a vacuum press, to hold them in position and minimise the chance of the veneers sliding around and getting out of position on the substrate.

    Can anyone please advise if using a few short strips of blue masking tape on each side to hold the three pieces together in the press will adversely impact on the finish? i.e., is it likely to indent the veneer, or affect the glued joint either side of the tape?
    regards,

    Dengy

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many





     
  3. #2
    Join Date
    Feb 2003
    Location
    back in Alberta for a while
    Age
    68
    Posts
    12,006

    Default

    Hi Dengy

    I'm not quite sure what you have done / are trying to do

    have you already glued the veneer to the MDF ? or is that what you want to do?


    You should:

    1. joint the edges of the veneer to give you crisp, straight 90° edges.

    2. Then lay the veneer upside down and use short pieces of blue painter's masking tape stretched across the join to pull the edges together

    3. turn the veneer right side up, and again using short pieces of painter's masking tape pull the joint together, then run a strip of blue tape down the joint

    4. remove the short pieces of tape from the reverse side

    you are now ready to glue to the substrate -- personally I prefer a long open time PVA over epoxy.


    good luck
    regards from Alberta, Canada

    ian

  4. #3
    Join Date
    Mar 2008
    Location
    Townsville, Nth Qld
    Posts
    4,236

    Default

    Thanks for your helpful reply, ian, there is some good information there.

    But my problem above refers to what happens after the two sheets of veneer are glued to either side of the substrate, and then put in a press. I want to prevent any movement of the veneer sheets on the substrate while putting it in the press, or during pressing.

    With the substrate having glue on both sides, and the veneer sheets on either side, you have a slippery combination where it is easy for one of the sheets to move. I am thinking of taping the three ( substrate and 2 sheets of veneer) together, bit am concerned about possible indentation or uneven-ness once the press is applied to the veneer with strips of blue painter's masking tape on the 4 sides.

    But from what you are saying above, it is quite normal to have veneer with blue painter's masking tape on top, and then put into the press
    regards,

    Dengy

  5. #4
    Join Date
    Nov 2004
    Location
    Stirling SA
    Age
    70
    Posts
    47

    Default

    Dengue

    I use blue tape all the time when veneering, similar to the way Ian described. I haven't had any problems with the tape denting the veneers.

    What does happen though, is the pressure makes the tape stick strongly to the veneer requiring a bit of careful effort to get it off. Paper veneer tape works well and come off with a bit of water.

    As with all things woodworking give it a try and see what happens. (on a test piece of course)

    Good luck.

    Bob


    Sent from my iPad using Tapatalk

  6. #5
    Join Date
    Apr 2006
    Location
    Hobart
    Posts
    5,105

    Default

    Good Morning Denghy

    Unlike Bob and Ian, I prefer to use paper "lick-on" tape rather than masking tape. A very light touch with the ROM will later remove all traces of paper and it is a dry process. Masking tape can grip too tight - occasional splinters on removal and glue stains.

    I also use 5mm nylon backing boards or cauls - the same size as the press - and PVA and epoxy do not stick to the nylon.

    My system is to:
    。roll even coat of PVA onto MDF,
    。carefully place veneer, smooth from centre outward to ensure good initial contact,
    。place nylon sheet on top,
    。gripping MDF and nylon, carefully flip it over, then
    。roll glue onto other side of MDF,
    。apply other sheet of veneer,
    。put second nylon sheet on top,
    。put everything in press and tighten hard,
    。ten minutes later, re-tighten press (glue oozes and I usually get a quarter of a turn),
    。next morning, remove from press; much/most paper tape will easily peal off. ROM with 300 grit will remove the rest.
    。admire your work!

    Initially I used epoxy, but PVA is easier to use and seems to glue just as well.

    Hope this helps.


    Fair Winds


    Graeme

  7. #6
    Join Date
    May 2007
    Location
    Sth Gippsland Vic
    Posts
    4,355

    Default

    Yeah , Masking tape is a bugger to get off after being pressed but it does work .

    There is a special tape with holes in it which has a water based glue that is made for holding veneer sheets together . It's probably just called veneer tape ? I think I got mine from the US . Or it could have been George feathers here in Melbourne . I forget where .

    When I watched the older tradesmen veneering years ago , and they didn't have the right tape they used hide glue and strips of news paper as tape .

    The bought laid up patterns of shells and leaves that I have seen are held with a more stout brown paper and hide glue .

    All this is to stop joints or jointed veneers shifting and hot water takes it off later .

    To stop veneer shifting from the position you want it to be stuck to its ground , veneer pins are used . Small brads are hammered into the ground and clipped off , leaving a small chisel like point .5 of a mm above the ground , put in as many as you think will do the job and lay the veneer over them and give a rub down with a hammer . this stops things shifting under pressure.

    Rob

  8. #7
    Join Date
    Feb 2003
    Location
    back in Alberta for a while
    Age
    68
    Posts
    12,006

    Default

    Quote Originally Posted by Dengue View Post
    Thanks for your helpful reply, ian, there is some good information there.

    But my problem above refers to what happens after the two sheets of veneer are glued to either side of the substrate, and then put in a press. I want to prevent any movement of the veneer sheets on the substrate while putting it in the press, or during pressing.

    With the substrate having glue on both sides, and the veneer sheets on either side, you have a slippery combination where it is easy for one of the sheets to move. I am thinking of taping the three ( substrate and 2 sheets of veneer) together, bit am concerned about possible indentation or uneven-ness once the press is applied to the veneer with strips of blue painter's masking tape on the 4 sides.

    But from what you are saying above, it is quite normal to have veneer with blue painter's masking tape on top, and then put into the press
    Dengue

    I'm assuming your press is unheated
    For pressing in a heated press, I'd only use paper veneer tape.

    normally the veneer would be slightly bigger than the ground, and the ground would be slightly bigger than the final size
    the veneer can be tacked to the ground with short pieces of tape at either the middle of each side, or the corners, or both

    I haven't had a problem with the tape leaving a depression in the veneer, but if you are at all worried use paper veneer tape.
    regards from Alberta, Canada

    ian

  9. #8
    Join Date
    Jul 2008
    Location
    north haven sa
    Posts
    3

    Default

    Quote Originally Posted by Dengue View Post
    After gluing two sheets of veneer on a MDF substrate with epoxy, I would like to tape them together before putting them in a mechanical press, or a vacuum press, to hold them in position and minimise the chance of the veneers sliding around and getting out of position on the substrate.

    Can anyone please advise if using a few short strips of blue masking tape on each side to hold the three pieces together in the press will adversely impact on the finish? i.e., is it likely to indent the veneer, or affect the glued joint either side of the tape?
    Dengue,
    This is the way I did it when I built my TV unit.The veneers(tas oak) were 4mm over 12mm mdf so nominal 20mm panel . No problems with tape impresions also reasonably easy to remove.both sides of the panel were glued in one go.Titebond 3 usedDSCN7929.jpg

  10. #9
    Join Date
    May 2003
    Location
    Central Coast, NSW
    Posts
    3,330

    Default staples and sacrificial cauls

    As always, with questions about veneering, the answer depends on what type of veneer are you using. If its veneer you've cut yourself then its probably 1-3mm thick so it can take a bit of sanding. If its commercial veneer then its 0.6mm thick, so generally I prefer to avoid anything fouling the face of the veneer.

    My preferred method is simply to bang a couple of staples in. The substrate is usually oversize, so just staple it where it wont matter.

    If you do decide to use tape then veneer tape is better. Its hard to buy though, so I make my own by using ordinary reflex paper and Uhu Gum (note that is Uhu GUM, not Uhu GLUE). Buy it at a craft store.

    Another good trick I stick with is to use a couple of inner cauls - just 16mm melamine coated hmr. When making these, with the cauls clamped together, drill a hole through each corner, so they line up perfectly. Get some pegs which fit snugly in the holes. When using them, do your glueup and assemble externally to the press, putting one sheet below the workpiece and one above, and the pegs in place in at least 2 corners to stop the cauls (and hence the veneers) from sliding about. Now slip the whole thing in the press. I find that when using a press like the one you showed us late last year then the final tightening of the scissor jack causes small lateral movements - using this method they still occur but dont affect the glue-up.

    Note that 'cauls' are the flat sheets, not the battens - common misconception.

    Having sacrificial cauls also minimizes wear and damage to the real cauls on your press.

    cheers
    Arron
    Apologies for unnoticed autocomplete errors.

  11. #10
    Join Date
    Mar 2008
    Location
    Townsville, Nth Qld
    Posts
    4,236

    Default

    Many thanks for this excellent post, Arron, there are some real practical tips there. I had put some melamine boards in my car jack press ( as cauls) as you suggest, but I like the idea of locating dowels in each corner
    regards,

    Dengy

  12. #11
    Join Date
    Mar 2008
    Location
    Townsville, Nth Qld
    Posts
    4,236

    Default

    Had to do a red cedar veneered lid today ( the deep red soft Qld cedar) 400 x 200 x 2mm that I had resawn. Used Techniglue epoxy because of the long term benefits of zero movement, plus a reasonable open time while applying the mixed epoxy.

    Set up two boards of 16mm melamine as suggested in the "neat trick" by Arron above, put 8mm locating dowels in each corner, and taped some of my wife's non stick baking and cooking paper to the two inside surfaces. That way the cauls need not be sacrificial. Put the veneered sandwich on the bottom melamine caul, then slotted the top caul into position over the dowels - easy as, no sliding movement of the workpiece, especially when carrying it all to the car jack veneer press.

    I used the non-stick baking paper because a) I want to use the cauls again and b) I find that I get smudges of epoxy on the outside surface of the veneer during the glue-up, and don't want the veneer outer surface sticking to anything; it gets a bit messy with epoxy squeezed out of the sandwich, and I have to sand it all off later, something I am not sure of doing successfully with any 0.6mm thickness commercial veneer, like Arron says above. Need to work out a way of gluing up with less mess - less glue for a start.

    press_04.JPG press_01.JPG press_06.JPG


    The pictures below how it looked today with the 16mm melamine cauls with nonstick paper taped to the inner surfaces. The dark timber in the middle of the sandwich is the 9mm thick moisture resistant MDF substrate, and you can see one of the locating dowels in the corner.


    press_09.jpg press_10.jpg press_11.jpg

    The press is designed to take up to 410 x 300 wide lids. My next job is a large knitting needle box for my sister, and it requires a 500 x 200 veneered sandwich lid, so will have my first go at a Roarockit vacuum press that I bought ages ago. Should be interesting, esp as I have hand trouble ( arthritis) with the little manual vacuum pump in the playing about that I have done. And I particularly don't like the bag sealing tape idea, so will be looking for a better method that is easier and more certain of sealing. But this will be the subject of another thread
    regards,

    Dengy

  13. #12
    Join Date
    May 2003
    Location
    Central Coast, NSW
    Posts
    3,330

    Default More issues

    Dengy, I can make some comments on a couple of the issues you raised in your last post.

    For getting the amount of glue right, I have found the best method is to get a flat bladed plastic spreader and cutting v shaped grooves in it myself. From experience, 1mm 'V's, 5mm apart is about right for spreading PVA for veneering. When I use this, I just go ahead and trust the tool and not have to rethink the amount of glue each time. It'll spread the glue not too thick (which will bleed through and make a mess on the surface) and not too thin (which could lead to dry patches which would be disastrous).

    I think its about right for epoxy too - though my experience is limited to the product Botecoat so maybe you should vary it for other products.

    For keeping the surface clean, I often use contact film. Its the clear stuff - 'Clear self adhesive book film'. It is sometimes for sale in Big W in 15 metre rolls for a bargain $5 - usually they just have the smaller rolls but the 15metre ones turn up from time to time. I often glue up simple marquetry/parquetry patterns and do the final assembly on upside down contact paper, which is a quick way of holding it all together without edge-glueing. However I do still use it for simple glue-ups of one piece veneers, especially when using very pale, semi-transparent veneers like sycamore. Just spread it over before beginning the glue-up. It keeps the surface clean of gluey thumbprints, minute iron filings from the press mechanism, and mildew spores. It peels off reasonably easily after pressing, though as always peel carefully with the grain with a timber like red cedar.

    If you are going to raid the pantry for something to provide clean separation then consider Glad Go-between Freezer Film.

    cheers
    Arron
    Apologies for unnoticed autocomplete errors.

  14. #13
    Join Date
    Apr 2006
    Location
    Hobart
    Posts
    5,105

    Default

    Nice posts, AAron & Dengue

    Love your "jack-a-press", Dengue.

    For glue ups, I just use a small paint roller - works well and is simple.

    For cauls, I use 5 mm (or is it 1/4 inch?) nylon sheets and then I do not need any contact film or baking paper or whatever to stop glue sticking where it ain't wanted. Also works well, and one less complication to deal with.


    Fair Winds

    Graeme

  15. #14
    Join Date
    Mar 2008
    Location
    Townsville, Nth Qld
    Posts
    4,236

    Default

    Thanks for your reply, Graeme. I actually use the small V toothed plastic trowel for spreading the epoxy, then flatten it with a 100mm disposable foam roller. I tried the mohair roller covers, but the nap seemed to stick to the epoxy, more so than the foam

    I like the idea of a nylon sheet - where do you get them, please Graeme?
    regards,

    Dengy

  16. #15
    Join Date
    Apr 2006
    Location
    Hobart
    Posts
    5,105

    Default

    Good Morning Dengue

    I stopped using epoxy for veneering years ago - too messy - and PVA seems to stick just as well. More foregiving! I use a 100mm "wool" roller or a 50mm foam roller - both work fine.

    Any plastics supplier will have the white nylon sheets - as used in cutting boards - in 2400 x 1200 mm sheets of varying thicknesses. Most will cut it and sell you just what you want. Suggest you make your cauls about 10mm smaller than your press.



    Fair Winds

    Graeme

Similar Threads

  1. How to do veneering
    By Dengue in forum WOODWORK - GENERAL
    Replies: 38
    Last Post: 26th November 2013, 10:49 PM
  2. Veneering help
    By andersonec in forum BOX MAKING
    Replies: 10
    Last Post: 6th November 2010, 06:57 AM
  3. Veneering problem
    By marcoolabob in forum BOX MAKING
    Replies: 4
    Last Post: 28th September 2010, 02:42 PM
  4. veneering help please
    By la Huerta in forum WOODWORK - GENERAL
    Replies: 4
    Last Post: 11th May 2006, 01:31 PM
  5. Veneering onto MDF.
    By DanP in forum WOODWORK - GENERAL
    Replies: 16
    Last Post: 16th November 2004, 07:35 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •