Best Varnish for Dobsonian

[Singlin]

I have been advised to use an oil based polyurethane semi gloss varnish, which I am having difficulty in finding here in Italy (they all seem to be water based these days)

Any suggestions?

[swamp thing]

How about lacquer? 

 

[Timebandit]

Hello. If I remember correctly when I was reading Faulksy DIY Dob 20" build,(professional build from the quality of work) Then I think Mike used a polyurethane varnish on his wood. It may be worth pm Mike and ask what he used. I hope Mike does not mind me saying.  I hope this helps 

[Putaendo Patrick]

If you can find a marine chandler or ship's supplier, they will probably have something appropriate. Stoppani do a line of varnishes for yachts:  http://www.lechler.eu/it/Home/Yachting/Catalogo-Prodotti-Yachting/PID/3318/mcat/3322/acat/1/nsw/t/EDNSearch/vernice

And here the technical pdf for one that may serve you: https://portal.lechler.eu/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=133447&Command=Core_Download

[Putaendo Patrick]

Also.....

A link to a page on varnish for guitars: http://www.frudua.com/vernici_per_liuteria.htm

Vernice bicomponenti might be interesting to explore.

And another manufacturer of yacht varnish: http://ecommerce.cecchi.it/productcart/pc/viewCategories.asp?idCategory=11

[ronin]

Noticed that here it is getting more common to find a water based varnish but most places still have Yacht Varnish stocked as well. The yacht varnish does take a day to dry but it should be highly water resistant. I did manage to find a fast drying polyurethane varnish and it was quick drying but it was a branded store item and you are not going to have it in Italy.

Only really seen the yacht varnish in gloss, but that was all I looked for. As said allow at least 24 hours and preferably 48 to dry.

[jabeoo1]

I use Fiddes hard wax oils to protect and seal woods. 

They do interior and exterior products:

http://www.wood-finishes-direct.com/product/exterior-wood-oil?gclid=Cj0KEQjwt-G8BRDktsvwpPTn1PkBEiQA-MRsBdOzrI588HFT4MCbDVQeyF-P8DZ_VDCeDF9IW2nHmFsaAuNF8P8HAQ

[Singlin]

Thanks for the input.

I bought a polyurethane semi gloss varnish and tried it on sone scrap ply.I am not happy as it turned yellow.I cant find a polyurethane that is completly clear.

[mapstar]

I searched for a long time to find something that doesn't yellow the wood. Here is some clear water based stuff that I used on top of the black for my scope. It is milky to look at in the tin but totally clear when applied and dries to a hard finish.

http://www.protekwoodstain.co.uk/clear-coats/royal-exterior-wood-finish-clear

Not sure if you can get it over there in Italy? It has low VOC (volatile organic compounds) as I have been informed that vapours given off by other paints can react with the mirror coatings so be wary if the stuff you end up with isn't. I've never used Yacht varnish but the finished wood I've seen done with it has a slightly tacky feel to it (could be just that make) which was not nice.

Anyway hopefully that may help a touch? 

[mapstar]

Just to add depending where it's kept and the quality of the paint the birch ply will naturally yellow over time if exposed to sunlight.

[Physopto]

17 hours ago, mapstar said:

I searched for a long time to find something that doesn't yellow the wood. Here is some clear water based stuff that I used on top of the black for my scope. It is milky to look at in the tin but totally clear when applied and dries to a hard finish.

http://www.protekwoodstain.co.uk/clear-coats/royal-exterior-wood-finish-clear

Not sure if you can get it over there in Italy? It has low VOC (volatile organic compounds) as I have been informed that vapours given off by other paints can react with the mirror coatings so be wary if the stuff you end up with isn't. I've never used Yacht varnish but the finished wood I've seen done with it has a slightly tacky feel to it (could be just that make) which was not nice.

Anyway hopefully that may help a touch? 

I always wondered if the tacky feel was due to the additives to stop the surface cracking. I know that a lot of clear car finishes used to be able to be altered for wood with the addition of a few drops of glycerine. At least that is what I was told years ago.

[Demon Barber]

Hello ,try this range,i have just used them on my Obsession ,and have turned out very well,they are only available from the States Canada,or Australia. Link here:https://www.amazon.co.uk/Minwax-Polycrylic-Protective-Finishes-24444/dp/B000BZZ3RO/ref=sr_1_1?ie=UTF8&qid=1470583548&sr=8-1&keywords=minwax

Watch the YOUTUBE Minwax channel they show you all the finnishes available.

These are the stains that Obsession,and Webster scopes.

They took just under 3 weeks to arrive    from theStates ,prices not to bad,

HTH,

Mike

[Singlin]

Thanks for the help.

I ended up applying the above floor semi gloss polyurethane varnish, when dry it looks ok.

 

[Singlin]

Will a water based balckboard paint with internal specifications be ok to apply on top of a sanded solvent  based polyurethane varnish?

The internal of my mirror box and mirror cell will be painted matt black.

Water based blackboard paint specs state that it is for internal use only, I don't envisage my dob being out in the rain?

Regards,

Simon

[Demon Barber]

Hi Simon,i use a blackboard paint over poly/u just make sure base coat is dry.

Good thing with black board paint is it dries in under an hour and is easily touched up if needed

Regards

Mike

[Singlin]

Cheers Mike.