Latest News: Forums Technical Sanding between coats

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  • #4291
    tempest51
    Member

    Hi,
    I’ve stripped my wooden decks, cleaned them to Swiebertje standard, first coated with 40% diluted 1 pot varnish, added 2 further coats. My question is related to sanding in betwen coats. Could somebody advise on just how hard or soft I need to rub down using 240 grit before applying the next coat? I have rubbed enough to get the white film showing up, but somehow feel that I have taken off too much varnish and am in danger of applying not enough varnish?

    #9985
    Colin Parkstone
    Participant

    Tempest, It sounds to me that you have answered your own question!
    If you feel you are sanding to hard and going through the varnish your putting on,sand lighter!
    I would have not thinned the varnish after the first coat and
    maybe let the varnish harden and sink more before the next coat.
    The varnish will sink more into stripped wood so your going to need more to replace it, I think your feelings are right!
    If i was varishing from bare would, ie New, I would start with two pack varnish as it is harder and fills the grain in the wood better, then go to one pot for the top coat if wanted!
    CP

    #9988
    Davdor7038
    Member

    I had the same problem with my seats. Also found the sandpaper clogged up very easily. In the end, I used washing up scrubs ( the ones with green scrub material and sponge combined)(cheap from Aldi/Lidl). The dust moved away from the contact area back into the remaining scrub material ( so no clogging up). Also, the green scrub material was just harsh enough to take away the glaze surface without removing too much Varnish and you can wash out the scrubs afterward, ready for another scrub tomorrow go when they dry out. Dave D.

    #10001
    tempest51
    Member

    Thanks chaps,

    I actually visited Peter Freebody’s on the Thames. One guy I chatted too was extremely knowledgeable and informative, and made much reference to cleaning the work area, watering the floor to hold down dust, the wearing of special clothing as in disposable plastic overalls, possibly using a foam rolller for speed, keeping a wet edge at all times etc. He concurred with me that I had been sanding far too heavily and that I should concentrate on only removing the shine from the previous coat, he reckoned on 5 light wipes with paper, 340 grade and higher. He also said that after 42 years, he still didn’t know the answers and that each project presented unique challenges. There are no short cuts, and the better the preparation the finer the finish. Get plenty of varnish on with each coat was his tip. Of course, they work on some beautiful motor launches such as Rivas. He was a fan of polyurethane though, but thought my choice of Hempel Classic was a good one. His parting piece of advice was to reckon on at least 12 coats….I translated that to 6 as my maths is not good.

    I like the idea of the kitchen scrubber Davdor, and will give it a go. Hope some of the above will help others

    #10004
    Colin Parkstone
    Participant

    By doing 12 coats now it will reduce the amount of sinking that the varnish will do in the next season and so reducing the need for a new coat of varnish the very next winter.

    If you were a Riva owner and you spent all that cash and then found you needed to varnish again the very next winter you would think the builder had ripped you off.

    So the reason you were told 12 coats now is for your own good unless your happy to varnish each year as lots of people are !!

    It does cover over the dumps and scrapes of the season.

    CP

    #10005
    tempest51
    Member

    Colin,
    If I were a Riva owner, the chap I spoke to would be knotting his hanky on the four corners each year, whilst sporting a rather fetching plastic transparent overall and cursing his decision to drop night school during the years immediately following the demise of Winston Churchill and removing the shine on my magnificent craft in preparation for its annual massage of the amber stuff. 😛

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