Advice on smoothing out a 1 coat, oil-based varnish

twofires · 1145

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Offline twofires

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on: August 27, 2021, 09:34:40 PM
Hi all. I'd appreciate a bit of advice on smoothing out the finish on my Crack base.

I've glued the base together, sanded, and stained with British Paints' Timber Protect One Coat Oil-based Stain (which went well), and then applied their matching clear coat (which went less well). The result is as per the attached photo.

Apparently sags and dust nibs like that are pretty common, but the advice on what to do about it varies. Some say lightly sand wet with 320 or so grit, then finer as required, others say use a much finer grit wet and spend more time on it. Some then say apply another coat (not sure if that's appropriate for a 'one coat' product like this), while others say buff wax into it.

The other complicating factor is that I chose a satin finish, not gloss.

I have no experience with any of this, but would prefer not to sand through the clear and remove stain underneath. How would you go about making this better, without risking making it worse?

Thank you in advance.

Simon

Simon N


Offline bernieclub

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Reply #1 on: August 28, 2021, 01:11:00 AM
Very fine wet sanding will work, but use an extreme light touch.   Fine steel wool is less likely to cause damage.

Bernie Zitomer


Offline Chris H

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Reply #2 on: August 28, 2021, 01:18:07 AM
I had similar issue when I built my first kit (Crack) 18 months ago (and in just about everything built since truth be told)
Unfortunately, I found a lot ended up being trial and error especially when it came to trying to correct a finish I was not happy with.
Instruction goes so far but getting a feel for how lightly or how much to sand only comes with trying.

I would be tempted to give a very light wet sand to take off the worst of the imperfections then apply another coat as required.  Subsequent coat needs a key so not too smooth.

More than once I sanded a little too heavy and removed the stain.  Trying to repair this was futile.  Complete strip and start again followed so be prepared for this if you choose to sand without extra coat.
However this did have the happy accident of leaving a nice dark layer in the grain.  Not the most efficient way of grain filling though.
I found that applying another coat just built up layers on any imperfections so whilst it would offer more protection against sanding through to the stain it does require a little more sanding to get the finish smooth again.
On a subsequent build I was able to correct without putting another coat on so either method can work but important to work lightly.
Once you have finish you like can buff/polish to the sheen you want.

Key thing to look out for (not sure whether this is common or just something I was doing) is that the ends and edges of a surface tended to sand down to the stain quicker.
I am not sure whether this is because the coat is thinner there or whether different sanding pressure is being applied, i suspect the former.

If it does go wrong, worst that can happens is needing to sand it back to the bare wood and start again.
For me and my limited ability, this actually takes less time than trying to fix a poor finish. 

I am sure there will be others with much greater experience and ability but it sounds like you are coming at it with similar experience to me so hope this helps.

Regards
Chris





Offline Markkr

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Reply #3 on: August 28, 2021, 08:49:31 AM
You’re going to think I’m crazy, but just try it…

Brown paper bag, use it like sand paper… someone recommended this to me a few years ago and its magical!



Offline johnsonad

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Reply #4 on: August 28, 2021, 10:42:05 AM
0000 steel wool going with the grain of the wood.

Aaron Johnson


Offline twofires

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Reply #5 on: August 28, 2021, 11:09:33 AM
Interesting. Thank you, all for your thoughts.

@bernieclub & @johnsonad - I'll have to grab some steel wool and experiment. Are there any issues with steel particles getting lodged in the wood, or is that unlikely due to the wood being so much softer?

@Chris H - That's great insight - thank you. Luckily I coated the inside too, so I have a good sized area with which to experiment with various abrasive options and pressures. Worst case, dark grain fill does sound pretty cool.

@Markkr - it doesn't sound that crazy, actually. A bit like using aluminium foil (with some kind of lubricant) on pitted chrome. I don't think it'll be enough to remove the runs, but I'll give it a go.

Simon N


Offline bernieclub

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Reply #6 on: August 28, 2021, 11:44:53 AM
No problem with metal particles.    Be sure that the surface you're working on is cured/dry, not at all tacky.

Bernie Zitomer


Offline twofires

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Reply #7 on: August 28, 2021, 11:47:21 AM
@bernieclub I'm being a good boy and waiting the full 7 days for it to dry. One day to go.

Simon N


Offline johnsonad

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Reply #8 on: August 28, 2021, 12:09:19 PM
Nope, I just wipe it down afterward with a cloth.  Most often I put more than one coat and use steel wool after each coat has dried completely.

Aaron Johnson