Bristol bubbles

[GJD]

Well into my redo the rails project - did 3 days sanding (!!!) and general prep - today I got my first coat of Bristol on - It's kinda wacky because there are 'bubbles' at every spot that had exposed bare wood - lots of em.

The bare wood areas constitute a minimal amount but I'm wondering if I can sand these down before my next coat - plan to go for 4 coats total (I only have till Sunday to finish!)

So what say ye - sand em and move on to the next coat - or am I missing something ???

Thanks guys

[CapetaniosG]

You can sand the bubbles down but the question you should be asking is why do the bubbles form? If you're applying the varnish during a day of sunshine ie. in direct sunlight you'll get bubbles. The best time is late afternoon or on a cloudy day. Avoid early mornings and I'll let you guess why.

capetaniosG

[GJD]

Thanks capetanios

It seems the only thing Bristol says is that wind (wtf?) can cause bubbles. Since the only spots bubbling were the bare wood (minimal) - now that they are covered with the first coat I just wanted to be sure light sanding was ok at this stage. Indeed I was in the sun - hot as hell - about 90 but Bristol suggests full sun is np.

Anyway - intend to knock out 2 more coats tomorrow then 220 sand and finish on Sunday - WHEW!

[MikeP]

There are a lot of complaints re Bristol and this specific problem on the internet. There were a lot of posts about contacting Bristol and their answer was always that the person complaining didn't follow the directions properly. I did a search on this when I was looking at products and it's the reason I decided not to use it when I stripped the Cetol off of everything. I went to regular varnish (Epifanes). I hope you will be able to overcome this problem but frankly, if it was me, I'd just call it a "lesson learned" and go with varnish.

[rrrestorer]

the urethane is drying too fast! your getting solvent popping, sand down the bubble" areas and redo, temps of 90 and over are hard for any finishes and doing it in direct sunlight which raises the temperature is suicide for the finishes. you're drying too fast , slow it down by using their tropical reducer and not doing it in the sun. A trick that we do with car finishes, all urethane now, is to use a reducer which lets it dry slower so that we get better layout and a glossier, smoother finish, never speed up the paint as it then doesnt flow out. Your problem again is too fast of a drytime! Sanding betwwen coats , when the paint is dry enough is always a good idea as you get a smoother and thus glossier finish when your done. the differance between a so , so finish and that deep , deep , shine that you see sometimes is a function of more coats and sanding in between them.---Pete

[Brian Degulis]

What's happening is the bare wood is gassing cause your putting it on as the wood is getting hotter. It's a problem with all coatings but it's more of a problem with 2 part urethanes because they skin over very qickly. I would sand them down then put on some of the bristol thinned down later in the day when the temp is cooling down. The obvious problem with this is that you want the coating to set up before the evening dew comes so you have to time it. After you have all the wood sealed you shouldn't have this problem any longer.

If you end up doing this again try putting some thinned west epoxy on all the bare areas then sand and put your top coats on it should eliminate this problem.

Brian

[REBrueckner]

In general, varnish on days of moderate temperature, low wind, low humidity..otherwise you are fighting the odds of a perfect job...

I agree with the posts so far. If the surface you are painting is at all hot or very warm to the touch, you need to wait for a cooler day...for the reasons cited...But don't varnish too late in the day...evening dampness will dull the finish if it's not completely set as dew sets...

In addition, when brushing you should lay the brush at an acute angle with your direction of motion....the brush handle needs to be pointing in the direction of your brush stroke.....DO NOT keep the brush vertical to the surface: the bristles will "pop up" as you lift the brush and induce bubbles...finish your application of each section with the lightest touch possible....I usually balance the brush in my hand so its barely touching the surface as I finish a section....any pressure from you will cause imperfections, although not usually bubbles unless you are using a "superman" stroke,....