# Hiding end grain



## philcav7 (Sep 12, 2013)

I'm going to be building a fireplace mantle that will have a few butt joints. 

I know there's multiple ways to seal & prep prior to paint, but I'm limited on time to start the project so a product from local SW or BM dealers may be best. There's a local lumber yard that builds cabinets so there's a chance the have proper putty/fillers available over the counter also. 


Wood will be raw poplar and some pre primed pine trim. I'm looking for an effective way to hide butt joints, seal it up, and make it beautiful. I will top coat with advance


----------



## woodcoyote (Dec 30, 2012)

Is this a paint grade project or stain?


----------



## PRC (Aug 28, 2014)

woodcoyote said:


> Is this a paint grade project or stain?


Sounds like paint. He's using preprimed and Advance topcoat.


----------



## woodcoyote (Dec 30, 2012)

Good call, didn't read it real well. 

Hide end grain, you could spackle the ends and sand smooth. Or edgeband them. Depending on how important the final look is, scope of work, etc.


----------



## philcav7 (Sep 12, 2013)

Yes, it will be paint. I've used spackle before, not sure why I didn't think of that. I have also used bondo in the past. They are readily available, but not sure if they are ideal for filling any minor seams in the joint that don't sand out, I would think bondo would crack, most spackle is vinyl based, but not sure how flexible it will be. I just don't want seams to telegraph due to seasonal humidity and heating cycles.


----------



## PRC (Aug 28, 2014)

philcav7 said:


> Yes, it will be paint. I've used spackle before, not sure why I didn't think of that. I have also used bondo in the past. They are readily available, but not sure if they are ideal for filling any minor seams in the joint that don't sand out, I would think bondo would crack, most spackle is vinyl based, but not sure how flexible it will be. I just don't want seams to telegraph due to seasonal humidity and heating cycles.


Dap plastic wood is a decent filler but will only resist so much stress from contraction. If there's that much cause for concern then the best would be epoxy. I used ART flex tec epoxy on the corner boards of custom bay windows during assembly. They were painted black and get very hot being on southwest exposure. So far they have not opened up.


----------



## woodcoyote (Dec 30, 2012)

If your worried about wood movement at the joints, the only thing I think that would work would be a flexible caulk. 

Sometimes if we are worried about it, we fill the joint with caulk and then flush it with spackle. 

I would use a wood filler that hardens. So you can sand it flush, then prime/paint.


----------



## PRC (Aug 28, 2014)

woodcoyote said:


> If your worried about wood movement at the joints, the only thing I think that would work would be a flexible caulk.
> 
> Sometimes if we are worried about it, we fill the joint with caulk and then flush it with spackle.
> 
> I would use a wood filler that hardens. So you can sand it flush, then prime/paint.


I have heard of this caulk then fill method before but what keeps the filler from cracking over the caulk since it is not flexible?


----------



## woodcoyote (Dec 30, 2012)

PRC said:


> I have heard of this caulk then fill method before but what keeps the filler from cracking over the caulk since it is not flexible?


Nothing.

It will end up cracking if the movement is large enough. And large enough can be milimeters, doesn't take much. 

The idea behind it is that if the spackle is thin enough on top then it won't crack as bad versus filling the entire joint with nothing but spackle. 

I've done both methods and the thin coat on top does work. If it does crack they are more like hair lines cracks. And the ones where they were filled completely the joints had much larger cracks. With hairline cracks, paint can sometimes be used to bridge the divide, so touchups are easier and faster. 

The caulking beneath also helps to act like a shock absorber as well, so it helps to not transfer the energy into the spackling, which will crack because it's hard.


----------



## woodcoyote (Dec 30, 2012)

Also I forgot to mention it's important to use the right caulking.

A lot of guys use the regular interior caulk/basic caulk and that won't help. It might hold it might not.

For wood joints or joint between sheetrock and wood we use, Shermax. A urethanized elastomeric caulk.

The Shermax is a Class 35 sealant, which means it can hold up to a 70% expansion....which is A LOT. Adhesion is good and I've never had an issue with it cracking like normal caulking.

If there is any exterior caulking to be done, I always use this type of caulking. And I've never had an issue with it. 

I have used other regular caulking (850A and 950A), which are also rated for exteriors, but not the high rating of Shermax. And guess what?? All the joints cracked and we had to redo all of them, trim on every window and door. So lesson learned.


----------



## PRC (Aug 28, 2014)

woodcoyote said:


> Also I forgot to mention it's important to use the right caulking.
> 
> A lot of guys use the regular interior caulk/basic caulk and that won't help. It might hold it might not.
> 
> ...


A few years ago we switched to urethane acrylic. It's the Allpro brand called ProStretch. Nothing but great results here too.


----------



## Andyman (Feb 21, 2009)

PRC said:


> A few years ago we switched to urethane acrylic. It's the Allpro brank called ProStretch. Nothing but great results here too.



Great product. About all I use for caulking these days. I've never understood how painters will spend $30-$60/gallon for paint and buy .99 caulking. The good stuff only cost $3. So you 'saved' $24 and sacrificed ever crack you painted!? It also tools so much better.


----------

